Data

Neckloop measurements

Neckloop and receiver-pair results, with field or level observations, frequency response, test conditions and reading limits.

15 rows
7 sources
Compiled 13 October 2026
Updated 13 October 2026
Version 1.0
Source dates: May 1985 – 8 September 2026

Data licence: CC0 1.0 (public domain dedication).

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Reading the results

Rows retain named models or receiver-neckloop pairs, alongside explicitly labelled summaries whose individual models are unavailable. Input voltage, magnetic field strength and relative frequency-response plots measure different things. Read the reference level, position and driving source with each result. Abstract-only findings retain their reading limits; personal-device paths concern shared coupling rather than venue performance. (Pro Audito Schweiz 2026; Hallikainen 2019; Hawkins and Schum 1985; Schafer et al. 2007)

Column definitions · Compilation and interpretation · Change log

Scroll horizontally to read all columns. Empty cells mean no value was recorded; read each row’s notes and limits with its results.

Neckloop measurements — 15 rows
Result ID	Model	Maker	Receiver or source	Row scope	Field strength or level	Input level	Frequency response note	Distortion or noise note	Test method	Conditions	Sample size	Test date	Source date	Source ID	Source locator	Funding detail	Scope	Limitations	Funding
pro-audito-2026-neckloops-iloop-plus	iLoop+	Geemarc	Bench drive not identified; no named receiver or phone output	model or pair	not reported	not reported	Most nearly flat high-frequency response of the six models; reduced low-frequency response	not reported	Pro Audito reports dummy-head measurements according to IEC 62489-1; relative frequency-response plot referenced to 1 kHz	Receiver output and dummy-head geometry not detailed; no separate phone-output result set. Active loop with integrated amplifier and battery	Six models in comparison; units per model not reported	not reported	2026-09-08	pro-audito-2026-neckloops	English reprint pp. 2, 6	Independent (Pro Audito Schweiz, Swiss hearing-loss association)	venue component	English translation of German report. Project funding not stated. No raw frequency samples or quantified distortion/noise; graph not digitized. Non-linear headphone outputs may change the response.	Independent
pro-audito-2026-neckloops-la-438	LA-438	Listen Technologies	Bench drive not identified; no named receiver or phone output	model or pair	400 mA/m (0 dB re 400 mA/m)	-12.7 dBu for the reported reference field	High-frequency roll-off, less pronounced than in the other passive models	Authors warn of distortion at maximum volume on weak headphone outputs; no distortion percentage reported	Pro Audito reports dummy-head measurements according to IEC 62489-1; relative frequency-response plot referenced to 1 kHz	Receiver output and dummy-head geometry not detailed; no separate phone-output result set. Passive loop; reported impedance 3-6 ohms at 1 kHz	Six models in comparison; units per model not reported	not reported	2026-09-08	pro-audito-2026-neckloops	English reprint pp. 3, 6	Independent (Pro Audito Schweiz, Swiss hearing-loss association)	venue component	English translation of German report. Project funding not stated. No raw frequency samples or quantified distortion/noise; graph not digitized. Non-linear headphone outputs may change the response.	Independent
pro-audito-2026-neckloops-il-200	IL 200	Beyerdynamic / Televic	Bench drive not identified; no named receiver or phone output	model or pair	400 mA/m (0 dB re 400 mA/m)	-6.4 dBu for the reported reference field	Marked high-frequency loss	not reported	Pro Audito reports dummy-head measurements according to IEC 62489-1; relative frequency-response plot referenced to 1 kHz	Receiver output and dummy-head geometry not detailed; no separate phone-output result set	Six models in comparison; units per model not reported	not reported	2026-09-08	pro-audito-2026-neckloops	English reprint pp. 4, 6	Independent (Pro Audito Schweiz, Swiss hearing-loss association)	venue component	English translation of German report. Project funding not stated. No raw frequency samples or quantified distortion/noise; graph not digitized. Non-linear headphone outputs may change the response.	Independent
pro-audito-2026-neckloops-ezt-3012	EZT-3012	Sennheiser	Bench drive not identified; no named receiver or phone output	model or pair	400 mA/m (0 dB re 400 mA/m)	+0.3 dBu for the reported reference field	Marked high-frequency loss	not reported	Pro Audito reports dummy-head measurements according to IEC 62489-1; relative frequency-response plot referenced to 1 kHz	Receiver output and dummy-head geometry not detailed; no separate phone-output result set	Six models in comparison; units per model not reported	not reported	2026-09-08	pro-audito-2026-neckloops	English reprint pp. 4, 6	Independent (Pro Audito Schweiz, Swiss hearing-loss association)	venue component	English translation of German report. Project funding not stated. No raw frequency samples or quantified distortion/noise; graph not digitized. Non-linear headphone outputs may change the response.	Independent
pro-audito-2026-neckloops-nl-90	NL-90	Monacor	Bench drive not identified; no named receiver or phone output	model or pair	not reported	not reported	Very strong high-frequency roll-off	not reported	Pro Audito reports dummy-head measurements according to IEC 62489-1; relative frequency-response plot referenced to 1 kHz	Receiver output and dummy-head geometry not detailed; no separate phone-output result set	Six models in comparison; units per model not reported	not reported	2026-09-08	pro-audito-2026-neckloops	English reprint pp. 5, 6	Independent (Pro Audito Schweiz, Swiss hearing-loss association)	venue component	English translation of German report. Project funding not stated. No raw frequency samples or quantified distortion/noise; graph not digitized. Non-linear headphone outputs may change the response.	Independent
pro-audito-2026-neckloops-nkl-001s	NKL-001S	Williams AV	Bench drive not identified; no named receiver or phone output	model or pair	not reported	not reported	Very uneven response; rising impedance with frequency makes the response depend strongly on the source. Authors found no acceptable result with the headphone outputs tried	not reported	Pro Audito reports dummy-head measurements according to IEC 62489-1; relative frequency-response plot referenced to 1 kHz	Receiver output and dummy-head geometry not detailed; no separate phone-output result set	Six models in comparison; units per model not reported	not reported	2026-09-08	pro-audito-2026-neckloops	English reprint pp. 5, 6	Independent (Pro Audito Schweiz, Swiss hearing-loss association)	venue component	English translation of German report. Project funding not stated. No raw frequency samples or quantified distortion/noise; graph not digitized. Non-linear headphone outputs may change the response.	Independent
hallikainen-2019-neckloop-notes-ntc-102	NTC-102	Comtek	IRH-230 infrared headset receiver	model or pair	>19 dB re 100 mA/m at loop centre (author-inferred full-volume lower bound)	Receiver at full volume; no-carrier noise, with no infrared signal present	not reported	No distortion or signal-to-noise ratio reported. Receiver no-carrier noise was the test stimulus	Manufacturer engineer used FoSmeter+ vertically at centre of neckloop lying flat on table. Reduced volume until unmarked loop read 0 dB, then compared loops at that setting	+3 dB relative to unmarked loop at reduced drive; approximate impedance 36 ohms, measured at 400 Hz through 12-ohm series resistor	Four neckloops identified; repeat count not reported	2012	2019-01-26	hallikainen-2019-neckloop-notes	Hallikainen reply at 11:32 AM; Hearing Aid Compatibility and field-strength table	Manufacturer (Harold Hallikainen's cinema-receiver test notes; the author describes the tested headphones as their own; neckloops and field-strength meter provided by Connections Unlimited; project funding not stated)	venue receiver and neckloop	Informal Manufacturer test notes. Centre readings exceeded meter range; >19 dB is inferred from +3 dB relative to the unmarked loop, whose full-volume field exceeded +16 dB. Table geometry does not reproduce a telecoil at the ear. Exact date of centre measurements not reported; notes place testing in 2012.	Manufacturer
hallikainen-2019-neckloop-notes-noizfree	NoizFree (no model number stated)	not reported	IRH-230 infrared headset receiver	model or pair	>19 dB re 100 mA/m at loop centre (author-inferred full-volume lower bound)	Receiver at full volume; no-carrier noise, with no infrared signal present	not reported	No distortion or signal-to-noise ratio reported. Receiver no-carrier noise was the test stimulus	Manufacturer engineer used FoSmeter+ vertically at centre of neckloop lying flat on table. Reduced volume until unmarked loop read 0 dB, then compared loops at that setting	+3 dB relative to unmarked loop at reduced drive; approximate impedance 27 ohms, measured at 400 Hz through 12-ohm series resistor	Four neckloops identified; repeat count not reported	2012	2019-01-26	hallikainen-2019-neckloop-notes	Hallikainen reply at 11:32 AM; Hearing Aid Compatibility and field-strength table	Manufacturer (Harold Hallikainen's cinema-receiver test notes; the author describes the tested headphones as their own; neckloops and field-strength meter provided by Connections Unlimited; project funding not stated)	venue receiver and neckloop	Informal Manufacturer test notes. Centre readings exceeded meter range; >19 dB is inferred from +3 dB relative to the unmarked loop, whose full-volume field exceeded +16 dB. Table geometry does not reproduce a telecoil at the ear. Exact date of centre measurements not reported; notes place testing in 2012.	Manufacturer
hallikainen-2019-neckloop-notes-ezt1011	EZT1011	Sennheiser	IRH-230 infrared headset receiver	model or pair	>19 dB re 100 mA/m at loop centre (author-inferred full-volume lower bound)	Receiver at full volume; no-carrier noise, with no infrared signal present	not reported	No distortion or signal-to-noise ratio reported. Receiver no-carrier noise was the test stimulus	Manufacturer engineer used FoSmeter+ vertically at centre of neckloop lying flat on table. Reduced volume until unmarked loop read 0 dB, then compared loops at that setting	+3 dB relative to unmarked loop at reduced drive; approximate impedance 33 ohms, measured at 400 Hz through 12-ohm series resistor	Four neckloops identified; repeat count not reported	2012	2019-01-26	hallikainen-2019-neckloop-notes	Hallikainen reply at 11:32 AM; Hearing Aid Compatibility and field-strength table	Manufacturer (Harold Hallikainen's cinema-receiver test notes; the author describes the tested headphones as their own; neckloops and field-strength meter provided by Connections Unlimited; project funding not stated)	venue receiver and neckloop	Informal Manufacturer test notes. Centre readings exceeded meter range; >19 dB is inferred from +3 dB relative to the unmarked loop, whose full-volume field exceeded +16 dB. Table geometry does not reproduce a telecoil at the ear. Exact date of centre measurements not reported; notes place testing in 2012.	Manufacturer
hallikainen-2019-neckloop-notes-unmarked	Unmarked neckloop	not reported	IRH-230 infrared headset receiver	model or pair	Centre: >16 dB re 100 mA/m with full-volume no-carrier noise; 6 inches above loop: +3 dB re 100 mA/m with full-volume no-carrier noise; 6 inches outside loop: +12 dB re 100 mA/m with programme audio	Centre and above-loop readings: receiver full-volume no-carrier noise; outside-loop reading: programme audio through IRC-28C infrared panel	not reported	No distortion or signal-to-noise ratio reported. No-carrier noise was the stimulus for the centre and above-loop readings; programme audio was used outside the loop	Manufacturer engineer used FoSmeter+ vertically at centre of neckloop lying flat on table. Reduced volume until unmarked loop read 0 dB, then compared loops at that setting	Loop flat on table for centre and above-loop readings. Approximate impedance 34 ohms at 400 Hz through 12-ohm series resistor. Above-loop and outside-loop notes dated 2012-08-13	Four neckloops identified; repeat count not reported	2012	2019-01-26	hallikainen-2019-neckloop-notes	Hallikainen reply at 11:32 AM; field-strength table and note ending hh 8/13/12	Manufacturer (Harold Hallikainen's cinema-receiver test notes; the author describes the tested headphones as their own; neckloops and field-strength meter provided by Connections Unlimited; project funding not stated)	venue receiver and neckloop	Informal Manufacturer test notes. Centre value is a lower bound beyond the meter range. Above and outside are distinct stated positions, combined here only to retain one row per receiver-neckloop pair. No ear-position measurement. The two unmarked entries in the source table describe the reference loop, not two identified models.	Manufacturer
hawkins-schum-1985-neckloop-summary	not reported	not reported	Two unidentified personal FM systems coupled to four hearing aids	study summary; models unavailable	not reported	not reported	Some coupling comparisons had large response differences; no coupling method consistently matched the hearing-aid-alone response best. Neckloop-specific curves unavailable	Distortion and noise were similar for hearing aids alone and FM-hearing-aid combinations except with the silhouette inductor	Electroacoustic measurement of frequency response, harmonic distortion, noise, input-output functions and receiver volume-wheel taper; compared hearing aids alone with direct input, neckloop and silhouette coupling	Some FM-hearing-aid combinations had strongly non-linear volume-wheel curves; abstract does not identify those pairs	Four hearing aids and two FM systems; number of neckloops not reported	not reported	1985-05	hawkins-schum-1985	Archived public abstract (PMID 3990259), methods and results	Independent (journal study; the archived abstract and metadata give no author affiliation or funder, and the full text was not read)	shared-path evidence	Abstract only. Personal classroom FM equipment, not venue receivers. Models, magnitudes and individual pair results unavailable. This is one pooled finding, not one identified model or every possible device combination. Funder not stated in abstract.	Independent
schafer-2007-neckloop-summary	not reported	not reported	Unidentified body-worn personal FM receiver(s) coupled to hearing aids via neckloop	study summary; models unavailable	not reported	not reported	Significant low-frequency reduction; greatest variability of the three receiver types	not reported	ASHA 2002 FM-advantage method; compared hearing-aid-alone and FM-system outputs at typical input levels using a complex signal and at high input levels using a pure tone	Compared body-worn neckloop, nonprogrammable ear-level and programmable ear-level receivers	Three receiver types; tested unit and hearing-aid counts unavailable in abstract	not reported	2007-10	schafer-2007	Archived public abstract (PMID 17890512), Method and Results	Independent (first author at the Speech and Hearing Sciences Department, University of North Texas; the PubMed record names no funder, and the full text, which may state one, was not read)	shared-path evidence	Abstract only. Personal FM fitting evidence, not venue receiver measurements. Models, numerical input/output levels and size of frequency loss unavailable. Funder not stated in abstract.	Independent
salzbrenner-1991-pocketalker-neckloop	Induction neckloop (model not stated)	not reported	Williams Sound PockeTalker personal amplifier; neckloop coupled to wearer telecoil	model or pair	not reported	not reported	Across tested devices, non-telecoil coupling gave broader and flatter responses; average telecoil versus non-telecoil differences were minimal. Both PockeTalker versions showed gain variation across samples at all frequencies	not reported	Madsen IGO 1000 in-situ probe-tube measurements of product uniformity, volume-control linearity, ear-coupling resonance effects and frequency response	not reported	One wearer; three samples of each of six device configurations, including PockeTalker with neckloop and permanently wired PockeTalker	not reported	1991-04	salzbrenner-1991	Archived public abstract (PMID 1829011)	Independent (Cleveland Hearing and Speech Center, Ohio, according to the PubMed record; no funder is named there)	shared-path evidence	Abstract only. Personal amplifier path, not a venue installation. Neckloop maker and model not stated; Williams Sound identifies the amplifier maker only. No numerical response differences or individual sample readings. Broader/flatter finding is a pooled comparison, not an isolated neckloop curve. Funder not stated in abstract.	Independent
rootlieb-2024-roger-neckloop-nucleus7	Roger Neckloop	Phonak	Apple MacBook Air source; Cochlear Nucleus 7 processor in telecoil mode	model or pair	Absolute levels unavailable: spectra aligned at 1 kHz; 65 dBA was a setup calibration target, not a measured neckloop field	not reported	Authors report generally less than 5 dB spectral differences above 500 Hz across wireless routes versus loudspeaker, with larger differences in some lower bands. Figure 1 includes the telecoil route; this is not a strict bound for every frequency	No quantified distortion or noise result for neckloop. Discussion notes magnetic-interference sensitivity	Speech-shaped masking noise through processor listening-check output, Samson Servo 120a amplifier and Sennheiser HDA 200 headphones on Bruel & Kjaer 4153 artificial ear with 2250 sound level meter; third-octave spectra	Neckloop suspended around processor; processor microphone and optional preprocessing disabled. Laptop substituted because smartphone could not connect. Placement affected volume	One processor model in telecoil condition; repeat unit count not stated. Separate listening experiment: 20 normal-hearing adults	not reported	2024-08-05	rootlieb-2024	Printed pp. 315-316, Experiment 1 Methods/Results, Table 1 and Figure 1; p. 318 Discussion	Independent (Amsterdam UMC; no funder is named and the authors report no conflict of interest)	shared-path evidence	Remote self-testing laboratory setup with personal devices, not venue equipment or implant-user listening. Readable full article with repository cover. Monitor-output spectra do not measure magnetic field or absolute implant output; no graph values digitized. Article names no funder. Source date is first online publication; issue is April 2025.	Independent
pro-audito-2025-operator-guidance-unnamed-pairs	not reported	not reported	Unidentified FM, infrared and Auracast transmitter-receiver-neckloop pairs	study summary; models unavailable	Required field at ear reached only with full transmitter drive and receiver volume usually at maximum; numerical measured field not reported	1 kHz sine wave; transmitter fully driven; receiver volume usually at maximum	not reported	not reported	Operator guidance reports magnetic-field measurements at the ear using a 1 kHz sine wave; meter and geometry not stated	not reported	not reported	not reported	2025-02-17	pro-audito-2025-operator-guidance	Section on magnetic field strength at the neckloop	Nonprofit advocacy (Pro Audito Schweiz, Swiss hearing-loss association)	venue receiver and neckloop	Unidentified pooled systems; cannot be assigned to specific models or counted as individual tested pairs. Guidance page has an unstated revision history, so its displayed date need not date the measurements. No raw readings or detailed protocol.	Nonprofit advocacy

Codebook

result_id: Unique source id plus a model or result suffix.
model: Neckloop model as identified by the source. An unidentified loop stays unidentified; the model of its amplifier is in receiver_or_source.
maker: Neckloop maker only. A source that identifies the amplifier maker does not necessarily identify the neckloop maker.
receiver_or_source: Driving receiver or audio source, with the receiving hearing device where relevant.
row_scope: model or pair, or study summary; models unavailable for pooled results that cannot be assigned to models.
field_strength_or_level: Reported magnetic field, qualified field lower bound, or explanation of why an absolute level is unavailable. Units, reference level and position remain with each value.
input_level: Input voltage or receiver drive condition. dBu describes electrical input, not magnetic field strength.
frequency_response_note: Measured response in the source's own comparison context, paraphrased. Pooled findings and normalized spectra are identified.
distortion_or_noise_note: Measured comparison, qualitative source warning, or absence of a reported result. A warning is not a measured distortion percentage; test noise is not a noise-performance result.
test_method: Instrument, signal, coupling route, reference and measurement procedure where stated.
conditions: Position, drive, impedance, processing and other setup details that affect interpretation.
sample_size: Devices, configurations or wearers where known; a separate listener study is identified separately. Unreported replication is not assumed to be one unit.
test_date: Measurement date at supported precision, or not reported. Publication dates are never substituted. The cinema notes place testing in 2012; the unmarked-loop row also identifies the two explicitly dated 13 August readings in conditions.
source_date: Publication or displayed source date, using YYYY-MM-DD or YYYY-MM. The operator-guidance page has an unstated revision history.
source_id: Library source identifiers supporting the row, separated by semicolons. Feature-specific and supporting-source columns retain their more precise roles.
source_locator: Original page, section, table or model entry supporting the row; source names identify locations when several originals are used.
funding_detail: Funding and producer context retained from the earlier compilation; the funding column carries the current source-record labels.
scope: venue component, venue receiver and neckloop, or shared-path evidence. Personal FM fitting, personal amplification and remote implant testing inform the shared coupling path, without establishing venue performance.
limitations: Row-specific interpretation limits and source-record reading limits. Missing information is not reported, never an inferred zero.
funding: Source-record funding labels. With multiple primary sources, each label is followed by its source id in brackets. Funding detail remains in funding_detail where supplied by the earlier compilation.

Compilation and interpretation

neckloops.csv was compiled and independently audited on 2026-10-13 from seven existing library records and their private archived originals. It contains 15 rows: six neckloop models from Pro Audito's dummy-head test, four receiver-neckloop pairs from Hallikainen's Manufacturer test notes, two personal-device paths, and three explicitly labelled study summaries whose individual models cannot be recovered from the readable material.

One row retains the results for a neckloop model or receiver-neckloop pair within one source. Multiple measurement positions for the same pair stay together with their individual conditions. The three study summary; models unavailable rows are exceptions to model-level granularity: they preserve the 1985 and 2007 abstract findings and Pro Audito's unnamed system tests without inventing device identities or expanding pooled results into individual pairs. Do not count those rows as three tested products.

The CSV is UTF-8, comma-delimited, with one header, double-quoted fields and LF line endings. Import all fields as text to preserve identifiers, partial dates, inequality signs and mixed measurement units. not reported means unavailable in the material read, never zero. The file contains no formulas, conversions, rankings or digitized graph points. Rows are grouped by source rather than performance.

The measurement types cannot be pooled into a product average. Pro Audito's three explicit sensitivity results give the electrical inputs for 400 mA/m; its frequency-response graph is relative to 1 kHz. The cinema notes use dB relative to 100 mA/m, with loops on a table: the three >19 dB values are the author's inferred full-volume lower bounds from a reduced-volume comparison after the reference loop exceeded the meter's range. The unmarked loop's centre, above-loop and outside-loop readings are different conditions. Rootlieb's processor-output spectra were aligned at 1 kHz, so their plotted absolute levels cannot supply a neckloop field or absolute device output. (Pro Audito Schweiz 2026; Hallikainen 2019; Rootlieb et al. 2024)

The 1985, 1991 and 2007 papers are represented only by archived public abstracts and metadata. Missing full-text models and numerical differences remain unavailable. The table preserves both adverse response findings and the reports of similar distortion/noise or small average coupling differences. Specifications without a reported test, standards targets, speech-recognition outcomes, general user impressions, latency and battery duration are outside this measurement table. The q22 research report lists screening decisions, archive provenance and existing-record concerns. (Hawkins and Schum 1985; Salzbrenner et al. 1991; Schafer et al. 2007)

For updates, read the source record and archived original first. Keep results from different sources or test conditions distinguishable. Replace a pooled summary with individual pair rows only when the underlying results become readable, retaining its provenance and documenting the change.

Change log

2026-10-13: Migrated 15 rows with codebook and source provenance into the data section.

Cite this table

Equal Access Audio. “Neckloop measurements” Assistive Listening Knowledge Base. Version 1.0. Compiled 13 October 2026; updated 13 October 2026. https://assistivelisteningknowledgebase.org/data/neckloops/ (accessed the date you read it).