Assistive Listening Knowledge Base
  • Manufacturer commissioning form (FRM 720D)

Induction Loop Certification

From https://assistivelisteningknowledgebase.org/evidence/williams-av-2021-loop-certification/ · record checked 13 October 2026

  • Williams AV

Manufacturer (Williams AV, for commissioning its loop amplifiers using its PC Mixer App)

Summary

A loop maker’s blank commissioning form records readings at seven positions and asks the facility manager to listen and sign at handover.

Key findings

  • Testing starts with normal venue electrical equipment and lighting running and the loop amplifier off; background magnetic noise is measured A-weighted relative to 400 mA/m.
  • Noise at or below -32 dB passes the initial check; between -32 and -20 dB the form calls for investigation and informing the facility manager, and above -20 dB it strongly recommends correcting the source before commissioning.
  • The 1 kHz field-strength step specifies 400 mA/m ±3 dB at the centre and six typical listening positions, marked on a retained floor plan, at seated or standing hearing height; it also asks whether the largest minus smallest reading is 6 dB or less.
  • The frequency-response table records 100 Hz, 500 Hz, 1 kHz, 2.5 kHz and 5 kHz at the same seven positions. The step’s introductory question names only 100 Hz, 1 kHz and 5 kHz.
  • Final handover asks the facility manager to check sound quality with a loop receiver and acknowledge that moving the app’s output faders changes calibration; both the field technician and facility manager sign.

Limits

A blank manufacturer form, not measurements from an installation or the IEC standard itself. It names no IEC edition. Its frequency-response step says hearing height is 5 feet, whereas the preceding step distinguishes seated and standing positions; its table includes more frequencies than its introductory question. Date is the printed 2021 copyright year, not the upload-directory date.

Read the original

williamsav.com/wp-content/uploads/2022/03/frm_720_loop_certification_SIMP_2021.pdf

Link checked . We link to the original and do not host copies.

Cited in

Cite this source

Williams AV. Induction Loop Certification. 2021. https://williamsav.com/wp-content/uploads/2022/03/frm_720_loop_certification_SIMP_2021.pdf (accessed 13 October 2026).

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