[Simulation of speech perception with cochlear implants : Influence of frequency and level of fundamental frequency components with electronic acoustic stimulation].
BACKGROUND
After implantation of cochlear implants with hearing preservation for combined electronic acoustic stimulation (EAS), the residual acoustic hearing ability relays fundamental speech frequency information in the low frequency range. With the help of acoustic simulation of EAS hearing perception the impact of frequency and level fine structure of speech signals can be systematically examined.


OBJECTIVE
The aim of this study was to measure the speech reception threshold (SRT) under various noise conditions with acoustic EAS simulation by variation of the frequency and level information of the fundamental frequency f0 of speech. The study was carried out to determine to what extent the SRT is impaired by modification of the f0 fine structure.


METHODS
Using partial tone time pattern analysis an acoustic EAS simulation of the speech material from the Oldenburg sentence test (OLSA) was generated. In addition, determination of the f0 curve of the speech material was conducted. Subsequently, either the parameter frequency or level of f0 was fixed in order to remove one of the two fine contour information of the speech signal. The processed OLSA sentences were used to determine the SRT in background noise under various test conditions. The conditions "f0 fixed frequency" and "f0 fixed level" were tested under two different situations, under "amplitude modulated background noise" and "continuous background noise" conditions. A total of 24 subjects with normal hearing participated in the study.


RESULTS
The SRT in background noise for the condition "f0 fixed frequency" was more favorable in continuous noise with 2.7 dB and in modulated noise with 0.8 dB compared to the condition "f0 fixed level" with 3.7 dB and 2.9 dB, respectively.


CONCLUSIONS
In the simulation of speech perception with cochlear implants and acoustic components, the level information of the fundamental frequency had a stronger impact on speech intelligibility than the frequency information. The method of simulation of transmission of cochlear implants allows investigation of how various parameters influence speech intelligibility in subjects with normal hearing.
Klinik für Hals-Nasen-Ohrenheilkunde/Abteilung Audiologische Akustik, Universitätsmedizin der Johannes Gutenberg-Universität Mainz, Langenbeckstraße 1, 55131, Mainz, Deutschland. tobias.rader@unimedizin-mainz.de.
T
T
Rader
AG Technische Akustik, MMK, Technische Universität München, München, Deutschland.
H
H
Fastl
Audiologische Akustik, Klinik für HNO-Heilkunde, Goethe-Universität Frankfurt am Main, Frankfurt am Main, Deutschland.
U
U
Baumann
D000161:Acoustic Stimulation / Q000379:methods*; D003054:Cochlear Implants; D019544:Equipment Failure Analysis / Q000379:methods*; D006801:Humans; D066230:Patient-Specific Modeling; D010898:Pitch Perception; D011474:Prosthesis Design; D012815:Signal Processing, Computer-Assisted; D013018:Sound Spectrography / Q000379:methods*
Cochlear implant; Computer simulation; Hearing preservation; Noise; Speech perception
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