Speech Segregation in Active Middle Ear Stimulation: Masking Release With Changing Fundamental Frequency

Area of Science:

• Audiology
• Speech Processing
• Hearing Implant Technology

Background:

• Temporal fine structure, including fundamental frequency (F0), is crucial for speech perception in noise.
• Cochlear hearing loss impairs temporal fine structure resolution, negatively impacting speech understanding.
• While active middle ear implants (AMEIs) offer improved sound quality, users often struggle in noisy situations.

Purpose of the Study:

• To determine if Vibrant Soundbridge AMEI users benefit from fundamental frequency (F0) differences between concurrent talkers.
• To compare the F0-based masking release in AMEI users with that of normal-hearing (NH) individuals.

Main Methods:

• 13 AMEI users and 13 NH individuals participated.
• A modified Oldenburg sentence test was used to create a concurrent talker scenario with varying F0 differences (4, 8, 12 semitones).
• Speech reception threshold was assessed adaptively, with AMEI users tested in two configurations (contralateral ear plugged and both ears plugged).

Main Results:

• Both AMEI users and NH individuals showed improved speech perception with increased F0 differences.
• A significant F0-based masking release was observed for AMEI users at F0 differences of 8 semitones (approx. 3 dB) and 12 semitones (approx. 3.5 dB).
• The masking release in AMEI users was comparable to, though slightly less than, that observed in NH listeners (approx. 5 dB).

Conclusions:

• AMEI users can achieve a masking release based on F0 differences in concurrent talker situations, particularly with an 8-semitone difference or greater.
• Occluding the ear canal did not significantly impact speech perception performance in AMEI users.
• These findings highlight the benefit of F0 processing for AMEI users, contributing to understanding low-frequency acoustic hearing.