Time Delay and Frequency Analysis of Remote Microphones.

Area of Science:

• Audiology
• Acoustics
• Assistive Listening Devices

Background:

• Classroom speech-to-text systems like A.BA.CO. use remote microphones (RMs) to reduce background noise.
• Signal latency differences between RMs and personal hearing devices (hearing aids [HAs] and cochlear implants [CIs]) pose challenges for users.
• Temporal coupling solutions are needed to synchronize audio streams for improved accessibility.

Purpose of the Study:

• To establish foundational data for a temporal coupling solution by measuring latency in RMs compatible with HAs and CIs.
• To analyze the frequency response of RM and HA systems, both independently and when combined.
• To assess the electroacoustic performance of RMs and HAs under varying conditions.

Main Methods:

• Electroacoustic measurements were conducted in a specialized laboratory.
• Two Behind-The-Ear HAs and two RMs were tested.
• The comparison method was used to assess performance with different compression ratios.

Main Results:

• RMs exhibited latency differences of 10-12 ms (23-35 ms range).
• HAs showed time delays differing by 1-2 ms (5-7 ms range).
• Combined RM and HA use with similar gains resulted in comb-filter distortions, affecting acoustic output.

Conclusions:

• Communication systems must account for brand- and model-specific RM delays.
• RMs are most effective when they are the primary sound source for the eardrum.
• The effectiveness of A.BA.CO. with RMs depends on these latency and acoustic interaction factors.