Electroacoustic verification of frequency modulation systems in cochlear implant users

Fidêncio, Vanessa Luisa Destro; Jacob, Regina Tangerino de Souza; Tanamati, Liége Franzini; Bucuvic, Érika Cristina; Moret, Adriane Lima Mortari

doi:10.1016/j.bjorl.2017.11.001

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Brazilian Journal of Otorhinolaryngology

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Original articles • Braz. j. otorhinolaryngol. 85 (2) • Mar-Apr 2019 • https://doi.org/10.1016/j.bjorl.2017.11.001 copy

Electroacoustic verification of frequency modulation systems in cochlear implant users^☆ ☆ Please cite this article as: Fidêncio VL, Jacob RT, Tanamati LF, Bucuvic ÉC, Moret AL. Electroacoustic verification of frequency modulation systems in cochlear implant users. Braz J Otorhinolaryngol. 2019;85:162-9.

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

Introduction:

The frequency modulation system is a device that helps to improve speech perception in noise and is considered the most beneficial approach to improve speech recognition in noise in cochlear implant users. According to guidelines, there is a need to perform a check before fitting the frequency modulation system. Although there are recommendations regarding the behavioral tests that should be performed at the fitting of the frequency modulation system to cochlear implant users, there are no published recommendations regarding the electroacoustic test that should be performed.

Objective:

Perform and determine the validity of an electroacoustic verification test for frequency modulation systems coupled to different cochlear implant speech processors.

Methods:

The sample included 40 participants between 5 and 18 year's users of four different models of speech processors. For the electroacoustic evaluation, we used the Audioscan Verifit device with the HA-1 coupler and the listening check devices corresponding to each speech processor model. In cases where the transparency was not achieved, a modification was made in the frequency modulation gain adjustment and we used the Brazilian version of the "Phrases in Noise Test" to evaluate the speech perception in competitive noise.

Results:

It was observed that there was transparency between the frequency modulation system and the cochlear implant in 85% of the participants evaluated. After adjusting the gain of the frequency modulation receiver in the other participants, the devices showed transparency when the electroacoustic verification test was repeated. It was also observed that patients demonstrated better performance in speech perception in noise after a new adjustment, that is, in these cases; the electroacoustic transparency caused behavioral transparency.

Conclusion:

The electroacoustic evaluation protocol suggested was effective in evaluation of transparency between the frequency modulation system and the cochlear implant. Performing the adjustment of the speech processor and the frequency modulation system gain are essential when fitting this device.

KEYWORDS
Cochlear implant; Assistive technology; Speech perception; Pediatric

Speech processor model	Brand	FM gain recommended
Harmony	Advanced Bionics	+10 dB
Freedom	Cochlear	0 dB
Nucleus 5	Cochlear	+2 dB
Opus 2	MED-EL	+10 dB

Participant	Speech processor model	Mean of CI microphone (dB)	Mean of CI + FM microphone (dB)	Difference (dB)
1	Harmony	74.6	75	0.4
2		79	78	1
3		78.3	80.3	2
4		75	79.3	4.3
5		87	85.3	1.7
6		81.3	80.6	0.7
7	Opus 2	72.6	75.6	3
8		67.6	69	1.4
9		71	74.6	3.6
10		72	75	3
11		73.3	71.3	2
12		74	73.6	0.4
13		78.6	77.3	1.3
14		75.3	74.4	0.9
15		68.6	64	4.6
16		73	76.6	3.6
17		64.6	67.3	2.7
18		78.6	82	3.4
19		72.6	75.3	2.7
20		66	67.3	1.3
21		77.3	78	0.7
22		74	75	1
23		70.6	72.6	2
24		79.6	82	2.4
25		54	53.6	0.4
26		78	79.6	1.6
27		78.6	80.6	2
28		71.6	74.6	3
29		70.6	71.6	1
30		73	76	3
31	Freedom	75.3	76.6	1.3
32		73.6	76	2.4
33		68.6	75	6.4
34	Nucleus 5	71.3	68.6	2.7
35		65.6	67.3	1.7
36		73.3	70.3	3
37		78.6	76.3	2.3
38		69.6	72	2.4
39		70	69.6	0.4
40		84.3	82.6	1.7

P	Initial gain (dB)	Result of the electroacoustic evaluation^a a With initial gain. (dB)	Speech perception in noise test^a a With initial gain. (dB)	Gain after adjustment (dB)	Result of the electroacoustic evaluation^b b After adjustment of gain. (dB)	Speech perception in noise test^b b After adjustment of gain. (dB)
4	+10	4.3	0	+8	1.7	-1.5
9	+10	3.6	-	-	-	-
15	+10	4.6	-	+12	1.3	-
16	+10	3.6	+6	+8	2	-1.5
18	+10	3.4	0	+8	0.3	-1.5
33	0	6.4	-	-	-	-

Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Sede da Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico Facial, Av. Indianópolia, 1287, 04063-002 São Paulo/SP Brasil, Tel.: (0xx11) 5053-7500, Fax: (0xx11) 5053-7512 - São Paulo - SP - Brazil
E-mail: revista@aborlccf.org.br

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[1] * Corresponding author. E-mail:vanessa.destrof@gmail.com (V.L. Fidêncio).

a	Connect the IC speech processor to its respective listening check device
b	Place one side of the earphone (listening check device) on the HA-1 coupler through the use of putty and place them in the Verifit test box
c	In the Verifit choose: "test" - "test box measures" - "speechmap"
d	Place the IC speech processor in the test box with the microphone next to the reference microphone (Verifit)
e	Close the equipment and select the stimulus intensity 65 dB SPL and stimulus type "Speech-ISTS"
f	Writhe down the values obtained in the frequencies of 750, 1000 and 2000 Hz and calculate a mean of these values

a	Adjust the gain of FM system (company's software)
b	Plug the FM system receiver into listening check device of the speech processor
c	To put the speech processor in the sound attenuation box
d	Put the microphone of the FM system transmitter in the test box (Verifit) near the reference microphone
e	In the Verifit choose: "test" - "test box measures" - "speechmap"
f	Close the equipment and select the stimulus intensity 65 dB SPL and stimulus type "Speech-ISTS"
g	Writhe down the values obtained in the frequencies of 750, 1000 and 2000 Hz and calculate a mean of these values