The PhD thesis submitted by Valentina Zapata Rodriguez presents an original set of four coherent
studies related to practical issues involved with measuring auditory steady state responses (ASSR)
in clinical environments. ASSRs are evoked auditory potentials elicited in response to repeated transient stimuli or modulated
tones and are ideal for early diagnostic screening and intervention methods for pre-lingual infants
and hard-to-test adults with hearing loss. In this technique, an acoustic stimulus is presented via a
loudspeaker near the listener's ear in an audiometric test room. While previous work has demonstrated
that ASSRs may be well suited for evaluating hearing aid fitting, these studies have typically
been conducted in acoustically controlled lab environments. Since room reverberation reduces amplitude
modulation and ASSRs are dependent on the amplitude modulations in the acoustic signal
received by the ear, the acoustic properties of the clinical test room could significantly influence
ASSR results.
Valentina Zapata Rodriguez's work is a valuable step forward in characterizing
the relationship between room acoustics and ASSRs and the examining committee agreed that Valentinas doctoral thesis is a valuable work in the field of hearing impairment
assessment and hearing aid fitting for patients who cannot reveal a voluntary response.
Through the well-organized document, it is demonstrated that the reverberation of the typical audiometric
test rooms reduces the level of ASSR, as well as its detection rate, and extends the testing
time. This work highlights the need for the development of acoustic standards for rooms suitable for
ASSR testing and identifies physical measures that are well suited for this purpose.
The examiners further agreed that the thesis is of high scientific quality and meets the standard for a PhD degree.
Congratulations to Valentina on her achievement.