Benefits of Bimodal Stimulation to Speech Perception in Noise and Silence

The present study included 13 participants aged between 16 and 80 years old who were users of cochlear implants from Cochlear Corporation and hearing aids. All patients underwent the Hearing in Noise Test, and their visual analog scale score was obtained. Four-tone means were collected, and the participants answered the Speech, Spatial and Hearing Qualities questionnaire.

Results

Bimodal users had an average sentence recognition rate of 76.0% in silence and 67.6% in fixed noise, and the signal-to-noise ratio in adaptive noise was +2.89dB. In addition, a lower level of difficulty was observed in the test using the visual analog scale. The domain with the highest average was auditory qualities (6.50), followed by spatial hearing (6.26) and hearing for speech (5.81). Individuals with an average between 50 and 70 dB of hearing level showed better sentence recognition in silence and noise.

Conclusion

Bimodal stimulation showed benefits for users with different degrees of hearing loss; however, individuals who presented greater hearing residue had better performance in speech recognition with noise and in silence in addition to a good perception of hearing quality.

Keywords
cochlear implant; hearing aids; hearing loss; speech perception

n	Sex	Chronological age (years old)	Hearing age (CI)	Hearing age (HÁ)	Deafness	Type and degree of hearing loss (CI)	Type and degree of hearing loss (HA)
1	F	31	7 months	84 months	Postlingual	SNHL profound	SNHL moderately severe
2	F	44	4 months	144 months	Postlingual	SNHL profound	SNHL profound
3	F	64	15 months	240 months	Postlingual	SNHL severe	SNHL severe
4	F	34	12 months	48 months	Postlingual	SNHL profound	SNHL severe
5	M	78	37 months	48 months	Postlingual	SNHL profound	MCSHL moderately severe
6	M	71	11 months	24 months	Postlingual	SNHL profound	SNHL severe
7	F	80	21 months	240 months	Postlingual	SNHL severe	SNHL moderate
8	F	65	58 months	240 months	Postlingual	SNHL profound	SNHL moderately severe
9	M	72	35 months	108 months	Postlingual	SNHL severe	SNHL profound
10	M	16	216 months	156 months	Prelingual	SNHL profound	SNHL severe
11	F	28	11 months	240 months	Prelingual	SNHL profound	SNHL moderate
12	F	38	25 months	432 months	Prelingual	SNHL profound	SNHL profound
13	F	26	10 months	192 months	Prelingual	SNHL profound	SNHL moderately severe

Variables	n	Average	median	Standard deviation	Minimum	Maximum	IQR (Q3–Q1)
Silence
CI	13	69.5%	61.1%	32.0%	1.3%	99.0%	54.0–91.7%
HA	13	49.1%	52.3%	36.3%	0.0%	98.8%	20.7–73.8%
Bimodal	13	76.0%	86.4%	26.2%	25.7%	100.0%	64.7–97.5%
Fixed noise + 10 dB
CI	13	50.6%	51.8%	36.1%	0.0%	98.3%	28.9–81.3%
HA	13	35.0%	33.7%	36.5%	0.0%	100.0%	0.0–59.6%
Bimodal	13	67.6%	72.7%	31.5%	0.0%	98.7%	60.3–92.5%
Adaptive noise
CI	8	+ 4.81dB	+ 3.95dB	+ 5.69dB	–2.10dB	+ 12.60dB	+0.3dB– +9.2dB
HA	6	+ 3.72dB	+ 3.90dB	+ 3.78dB	–1.00dB	+ 8.80dB	+0.8dB– +6.1dB
Bimodal	10	+ 2.89dB	+ 2.90dB	+ 3.41dB	–0.80dB	+ 10.00dB	+0.1dB– +4.0dB

Variables	CI		HA		Bimodal
Variables	Correlation	p-value	Correlation	p-value	Correlation	p-value
Silence
CI	1.00	–	–	–	–	–
HA	–0.30	0.313	1.00	–	–	–
Bimodal	0.82	0.001	–0.01	0.971	1.00	–
Fixed noise + 10 dB
CI	1.00	–	–	–	–	–
HA	–0.29	0.337	1.00	–	–	–
Bimodal	0.66	0.013	0.11	0.713	1.00	–
Adaptive noise
CI	1.00	–	–	–	–	–
HA	–0.40	0.750	1.00	–	–	–
Bimodal	0.31	0.453	0.20	0.783	1.00	–

VAS	n	Average	Median	Standard deviation	Minimum	Maximum	IQR (Q3–Q1)
Silence
CI	13	3.69	2.00	3.42	0.00	9.00	1.0–6.0
HA	12	5.17	5.00	3.13	1.00	10.00	2.7–7.3
Bimodal	13	2.85	4.00	2.54	0.00	8.00	0.0–4.0
Fixed noise + 10dB
CI	10	4.10	4.00	2.81	0.00	8.00	2.0–6.7
HA	8	3.87	3.00	2.64	1.00	9.00	2.0–5.2
Bimodal	13	2.85	4.00	2.54	0.00	8.00	0.0–4.0
Adaptive noise
CI	9	7.00	7.00	1.87	4.00	10.00	6.0–8.0
HA	7	6.71	8.00	2.69	3.00	10.00	4.5–8.5
Bimodal	11	5.91	6.00	1.37	3.00	8.00	5.0–7.0

VAS	CI		HA		Bimodal
VAS	Correlation	p-value	Correlation	p-value	Correlation	p-value
Condition of silence
CI	1.00	–	–	–	–	–
HA	–0.28	0.375	1.00	–	–	–
Bimodal	0.54	0.056	0.25	0.440	1.00	–
Fixed noise + 10dB
CI	1.00	–	–	–	–	–
HA	0.15	0.781	1.00	–	–	–
Bimodal	0.61	0.061	0.10	0.818	1.00	–
Adaptive noise
CI	1.00	–	–	–	–	–
HA	0.20	0.741	1.00	–	–	–
Bimodal	0.08	0.841	–0.03	0.953	1.00	–

Domains	n	Average	Median	Standard deviation	Minimum	Maximum	IQR (Q3–Q1)
\|Hearing for speech	12	5.81	5.30	1.98	3.60	9.40	4.0–7.2
Spatial hearing	12	6.26	6.15	1.93	3.00	9.00	5.2–8.0
Auditory qualities	12	6.50	6.38	2.40	2.25	11.80	5.2–7.3

Variables	Hearing for speech		Spatial hearing		Auditory qualities		Total
Variables	Correlation	p-value	Correlation	p-value	Correlation	p-value	Correlation	p-value
Silence
CI	0.42	0.173	0.36	0.253	0.12	0.720	0.20	0.528
HA	–0.05	0.870	–0.14	0.653	0.24	0.452	0.02	0.948
Bimodal	0.49	0.108	0.38	0.224	0.22	0.483	0.22	0.499
Fixed noise
CI	0.38	0.216	0.32	0.314	0.17	0.606	0.22	0.496
HA	–0.01	0.982	–0.19	0.548	0.26	0.413	0.05	0.887
Bimodal	0.64	0.025	0.44	0.158	0.44	0.150	0.41	0.193
Adaptive noise
CI	–0.45	0.268	0.36	0.389	–0.05	0.935	–0.07	0.882
HA	–0.20	0.714	–0.52	0.288	–0.43	0.419	–0.60	0.242
Bimodal	–0.45	0.222	–0.17	0.666	–0.36	0.339	–0.33	0.391

Audiometry Averages	Silence		Fixed noise + 10dB		Adaptive noise
Audiometry Averages	n	Average	n	Average	n	Average
50–70dB NA	5	71.0%	5	54.0%	4	+ 4.4 dB
71–90dB NA	4	29.0%	4	23.0%	1	+ 0.0 dB
≥ 91 dB NA	4	42.0%	4	23.0%	1	+ 4.5 dB

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[1] Address for correspondence Fayez Bahmad Jr, Health Science School, University of Brasilia, SMHN QD 02 BLOCO C ED DR CRISPIM SALA 515 ASA NORTE, Brasilia, Federal District 70710149, Brazil. (e-mail: fayezbjr@gmail.com).