HSC Section 8_April 2017

For example, a recent systematic review by Peters et al.

concluded that neither the CROS nor BAHD offered

much benefit for speech perception in noise (18), whereas

a review by Baguley et al. suggested some benefits for

both devices but more so for the BAHD (10). Improve-

ments in sentence perception in noise, when noise is de-

livered to the better ear, have been documented for the

CROS (19) and for the BAHD (20,21). Similarly, im-

provements have been reported for the BAHD when noise

is delivered to the front (12,13). Both devices have been

shown to impair speech perception when noise is on the

side of the poorer ear (12,13,19,22); in this condition, the

CROS or BAHD transmits the noise from the poorer to

the better ear and thus interferes with the speech signal.

Moreover, subjective benefits have been reported for the

BAHD and CROS, as measured by standardized self-

assessment questionnaires such as the Abbreviated Pro-

file of Hearing Aid Benefit (12,16,19,21).

A few researchers have examined the performance of

the BAHD and CROS within the same study, thus allow-

ing direct comparison between the two devices in the

same sample of participants (10

12,14,15,17,18,23,24).

Generally, the results of these studies have favored the

BAHD over the CROS based on subjective preference

and outcome measures using self-assessment question-

naires and on speech perception in noise. However, there

are a number of methodological issues present in most

of these studies (10,23). Firstly, in most studies, the

CROS was always fitted before the BAHD, so there was

no randomization, and in some studies only CROS fail-

ures were implanted with BAHD. Only Arndt et al.

(3) and Hol et al. (14) attempted randomization, but they

compared the CROS to a BAHD on a headband (i.e., non-

implanted), which attenuates the high frequencies (25)

and can be uncomfortable.

The goal of the current study is to address the need

for research comparing recent models of wireless CROS

hearing aids, with technologies such as digital noise

reduction and directional microphones, to BAHD with

similar technologies. To allow randomization while not

using a BAHD headband, this study used existing im-

planted BAHD users, assigned to either their BAHD or a

CROS in random order for a 2-week period, and mea-

sured auditory and subjective measures of perceived

benefit.

MATERIALS AND METHODS

Participants

Of nine adult SSD BAHD users recruited, one dropped out,

leaving eight participants (one male, seven female, age range

66 yr, average 54 yr) each with BAHD experience of 0.5 to

2.5 years. The BAHD were programmed using BC direct and

fine-tuned according to the patients’ comments when necessary;

the devices were verified using aided soundfield thresholds.

Adaptive directional microphone and noise reduction algorithm

were active. None of the participants had tried CROS hearing

aids before BAHD implantation. Participants’ characteristics are

displayed in Table 1.

Procedure

Participants’ performance was compared between their own

BAHD and the wireless Unitron Tandem 4 CROS hearing aid,

using a within-subject repeated measures design. Data were

collected over three one-and-a-half-hour visits spread 2 weeks

apart. Audiometric tests were administered in a double-walled

sound booth, using a Grason-Stadler GSI-61 audiometer cali-

brated according to ANSI S3.6 2010 standards, with the par-

ticipants sitting 1 m away from the loudspeakers.

Unaided Measures

Firstly, the hearing loss was measured for both air and bone

conduction using insert earphones. Soundfield thresholds were

then obtained with warble tones presented at 90 degrees azimuth

to the better ear and at 90 degrees azimuth to the poorer ear, the

difference being calculated as the head shadow.

Next, unaided monosyllabic word recognition and the QuickSIN

test were administered. The order of word recognition and

QuickSIN testing was counterbalanced across participants. Word

recognition was tested with the recorded version of the CID W-22

(Auditec of St. Louis), with a different list of 25 monosyllabic

words presented at 50 dB HL in three randomized listening

conditions: (a) with no noise (quiet) with words presented at

90 degrees azimuth to the poorer ear; (b) with words presented

from the front (0 degree azimuth), and multitalker noise (at 45 dB

HL) presented at 90 degrees azimuth to the poorer ear (S0Npe);

and (c) with words presented from the front and multitalker noise

(at 45 dB HL) at 90 degrees azimuth to the better ear (S0Nbe).

The QuickSIN test (Etymotic Research) consists of recorded

lists of six short sentences spoken by a female speaker in

multitalker background noise. The multitalker noise gradually

increases with each sentence presentation such that the signal-

to-noise ratio decreases from 25 to 0 dB, in 5-dB steps, over the

six sentences. The test measures the signal-to-noise ratio loss

(SNR) with a smaller score indicating better performance. The

TABLE 1.

Participants’ age, pure tone hearing threshold average, model of BAHD implanted, and length of implantation

at enrollment in the study

ID Age PTA (dB HL) Better Ear

PTA (dB HL) Poorer Ear

BAHD Model

Length of Implantation Implanted Ear

Cochlear BP100

1 yr

Right

Cochlear BP100

2.5 yr

Left

Oticon Medical Ponto Pro

1 yr

Left

Oticon Medical Ponto Pro

1 yr

Left

Oticon Medical Ponto Pro

1 yr

Right

Oticon Medical Ponto Pro

1 yr

Left

Cochlear BP100

2.5 yr

Left

Cochlear BP100

2.5 yr

Left

PTA indicates pure tone average unaided thresholds for 500, 1,000, 2,000, 3,000, and 4,000 Hz; NR, no response.

J. FINBOW ET AL.

Otology & Neurotology, Vol. 36, No. 5, 2015

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