How much do crowds, phones and Wi-Fi reduce reliability?

Why it matters

An empty-site test did not reveal the reception problems later found at one crowded outdoor event. The testers observed body obstruction and suspected additional interference from phones and other Bluetooth devices; they did not measure those devices' traffic separately¹.

What the evidence shows

• Crowds and line of sight. In Pro Audito's independent field test at an outdoor event of about 2,000 people (the number of tested receivers was not stated), reception without line of sight was "practically always unacceptable", and the authors suspect that the many phones and other Bluetooth devices added packet loss¹.
• Full rooms and Wi-Fi. A Swiss expert writes that in a fully occupied room with heavy Wi-Fi, the distance for interference-free reception can be considerably shorter than in an empty room².
• Interference shows up as lost audio frames. In a Ghent University/imec study with a Cochlear co-author, funded by imec and Flanders Innovation & Entrepreneurship, simulations found that more advanced packet loss concealment tolerated more of them, and overlap with Wi-Fi channels in use made frame loss vary widely³.
• Repetition helps against Bluetooth traffic. In a second Ghent University/imec study with a Cochlear Technology Centre co-author (funded by imec and Flanders Innovation & Entrepreneurship through the imec.icon BLE2AV project), one busy Bluetooth LE connection on a cabled testbed caused about 2% to 13% audio-frame loss in a broadcast with no repeated transmissions and none with one repetition; simulations found that two repetitions were needed to stay below the authors' frame-loss threshold once about 10 busy connections, or 20 keyboards plus 20 mice, overlapped the broadcast⁴.
• Coexistence inside one product. An engineer at a module maker reports that with Wi-Fi and LE Audio in one chip, a broadcast drove Wi-Fi throughput "practically to zero" until coexistence settings were re-tuned, while the LE Audio stream stayed undisturbed. This concerns radios inside one product, not interference measured across a venue⁵.
• Makers' advice. One maker advises mounting transmitters high to keep bodies out of the signal path and away from Wi-Fi access points, reducing power when many transmitters share a building, and a lower sample rate where interference is high⁶. Another treats poor audio at high signal strength as a sign of interference from Wi-Fi or wireless DMX⁷.
• Untested risks. RNID names congestion from thousands of 2.4 GHz devices in busy transport settings, and spoofed announcement streams, as risks that need practical trials⁸. An independent university security paper, with funding not stated in the paper, reports that encrypted broadcast authentication relies on a shared Broadcast_Code; attackers who know that code can impersonate broadcasts or disrupt reception⁹.
• European rules. Under the harmonised standard, equipment that does not adapt to other users of the band and transmits at 10 dBm e.i.r.p. or more is limited in how much airtime it may use¹⁰.

Where sources disagree

Sources disagree on transmit power. The SIG advises the lowest power that reliably covers the intended area^11,12, and one maker advises reducing power where many transmitters share a building⁶; a Swiss expert advises theatres to use maximum power and not to reduce it to limit range².

Otherwise there is little direct disagreement. The evidence is field observation, manufacturers' guidance and laboratory models. In the cabled study, channel maps excluded Bluetooth channels overlapping selected Wi-Fi channels, but no Wi-Fi traffic was transmitted⁴.

What would settle it

Measurements of packet loss and signal in occupied venues, with the Wi-Fi load recorded, across several venue types would help separate body obstruction from radio interference, which the outdoor report suspected and the cabled study did not test with live Wi-Fi traffic^1,4.

Planning while it is open

• Test with the room occupied^11,1.
• Run a quality-of-service test with Wi-Fi and other systems running as in normal use, and agree any power or frequency changes with the venue^13,7.
• Mount transmitters high and away from Wi-Fi access points⁶.
• Measure audio continuity as well as signal strength; where audio is poor despite a strong signal, look for interference by switching other 2.4 GHz services off and on^3,7.

Sources

1. Auracast practical test outdoors. Pro Audito Schweiz. Pro Audito Schweiz; English reprint by the Center for Hearing Access, 16 September 2026. Independent (Pro Audito Schweiz, Swiss hearing-loss association) ↩︎ https://centerforhearingaccess.org/wp-content/uploads/Pro-Audito-Schweiz-Auracast-practical-test-outdoors.pdf
2. Bluetooth Auracast in theaters and event venues. Graf B (Pro Audito Schweiz). Proscenium no. 3, pp. 10-11, Swiss Association of Technical Stage and Event Industry; English reprint by the Center for Hearing Access, September 2026. Nonprofit advocacy (Pro Audito Schweiz, Swiss hearing-loss association) ↩︎ https://centerforhearingaccess.org/wp-content/uploads/Proscenium-Technical-article-Bluetooth-Auracast-in-theaters-and-event-venues-1.pdf
3. Evaluation of BLE-based audio broadcasting under probabilistic interference. Baert M, Moons B, Pittevils J, Song Y, Madhu N, Hoebeke J. Computer Communications 222:130-140, June 2024. Independent (Ghent University and imec; funding from imec and Flanders Innovation & Entrepreneurship; co-author Jowan Pittevils is affiliated with manufacturer Cochlear) ↩︎ https://www.sciencedirect.com/science/article/abs/pii/S0140366424001634
4. Experimental validation of a Bluetooth-based speech audio broadcasting model. Baert M, Pittevils J, Moons B, Hoebeke J. IEEE PIMRC 2024 (imec-IDLab, Ghent University; Cochlear Technology Centre), 2 September 2024. Independent (Ghent University and imec; imec.icon BLE2AV project financed by imec and Flanders Innovation & Entrepreneurship; one co-author from Cochlear Technology Centre) ↩︎ https://doi.org/10.1109/PIMRC59610.2024.10817355
5. Bluetooth LE Audio in the real world: tackling RF issues, interoperability, and use-case diversity. Apel C (StreamUnlimited). audioXpress (print issue December 2025; online 11 March 2026), December 2025. Manufacturer (StreamUnlimited, maker of audio streaming modules) ↩︎ https://audioxpress.com/article/bluetooth-le-audio-in-the-real-world-tackling-rf-issues-interoperability-and-use-case-diversity
6. Infinium system controller and transmitter user manual (MAN 297B). Williams AV, 2026. Manufacturer (Williams AV) ↩︎ https://williamsav.com/wp-content/uploads/2025/08/MAN-297B-Infinium-Controller-Transmitter-BA-CT1.pdf
7. Auri user guide: RX1 commissioning tools (UP3B613-1). Listen Technologies and Ampetronic (Auri). Ampetronic, 2025. Manufacturer (Listen Technologies and Ampetronic) ↩︎ https://www.ampetronic.com/wp-content/uploads/UP3B613-01-Auri-User-Guide-RX1-Commissioning-Tool_A4_WEB.pdf
8. Auracast: a revolution in audio accessibility (RNID Auracast report). RNID (Royal National Institute for Deaf People). RNID, 11 February 2025. Nonprofit advocacy (RNID, UK charity) ↩︎ https://rnid.org.uk/wp-content/uploads/2025/02/Final-Auracast-Report-110225.pdf
9. BACON: improving broadcast audio authentication. Gasteiger T, Perazzo P, Schuß M, Boano CA, Basic F, Dini G, Römer K. IEEE MILCOM 2024 (Graz University of Technology; University of Pisa), 28 October 2024. Independent (Graz University of Technology; University of Pisa); funding not stated in the paper ↩︎ https://doi.org/10.1109/MILCOM61039.2024.10774045
10. ETSI EN 300 328 V2.2.2: wideband transmission systems; data transmission equipment operating in the 2.4 GHz band. ETSI Technical Committee ERM. European Telecommunications Standards Institute, 1 July 2019. Standards body (ETSI, the European Telecommunications Standards Institute) ↩︎ https://www.etsi.org/deliver/etsi_en/300300_300399/300328/02.02.02_60/en_300328v020202p.pdf
11. Auracast simple transmitter best practices guide, version 3. Bluetooth SIG, 17 October 2025. Standards body (Bluetooth SIG, an industry association funded by its member companies, which owns the Auracast trademark) ↩︎ https://www.bluetooth.com/wp-content/uploads/2022/10/Auracast-Transmitter_Recommendations.pdf
12. How to build an Auracast transmitter: technical overview, version 3. Bluetooth SIG Market Development. Bluetooth SIG, 16 September 2026. Standards body (Bluetooth SIG, an industry association funded by its member companies, which owns the Auracast trademark) ↩︎ https://www.bluetooth.com/wp-content/uploads/2024/05/2403_How_To_Auracast_Transmitter.pdf
13. Auri coverage and install guide (application note UP3B609-01, rest-of-world edition). Listen Technologies and Ampetronic (Auri). Ampetronic, 17 April 2025. Manufacturer (Listen Technologies and Ampetronic) ↩︎ https://www.ampetronic.com/wp-content/uploads/UP3B609-01_RoW_Auri-Coverage-and-Install-Guide.pdf

Change log

• 10 October 2026Published with 13 sources.
• 13 October 2026Separated field observations, laboratory interference and product-level coexistence; qualified the evidence gaps.
• 13 October 2026Independent audit corrected research attribution, funding and the scope of security and retransmission findings.
• 19 October 2026Corrected the funding statement for the cabled testbed study to match the paper's first-page acknowledgment.

Cite this question

Every finding here cites its source, and who funded each source is labelled. This site does not recommend products. Found an error or a missing study? Suggest a correction, or see how suggestions are handled.