BackgroundTelecommunication is limited or even impossible for more than one-thirds of all cochlear implant (CI) users.ObjectiveWe sought therefore to study the impact of voice quality on speech perception with voice over Internet protocol (VoIP) under real and adverse network conditions.MethodsTelephone speech perception was assessed in 19 CI users (15-69 years, average 42 years), using the German HSM (Hochmair-Schulz-Moser) sentence test comparing Skype and conventional telephone (public switched telephone networks, PSTN) transmission using a personal computer (PC) and a digital enhanced cordless telecommunications (DECT) telephone dual device. Five different Internet transmission quality modes and four accessories (PC speakers, headphones, 3.5 mm jack audio cable, and induction loop) were compared. As a secondary outcome, the subjective perceived voice quality was assessed using the mean opinion score (MOS).ResultsSpeech telephone perception was significantly better (median 91.6%, P<.001) with Skype compared with PSTN (median 42.5%) under optimal conditions. Skype calls under adverse network conditions (data packet loss > 15%) were not superior to conventional telephony. In addition, there were no significant differences between the tested accessories (P>.05) using a PC. Coupling a Skype DECT phone device with an audio cable to the CI, however, resulted in higher speech perception (median 65%) and subjective MOS scores (3.2) than using PSTN (median 7.5%, P<.001).ConclusionsSkype calls significantly improve speech perception for CI users compared with conventional telephony under real network conditions. Listening accessories do not further improve listening experience. Current Skype DECT telephone devices do not fully offer technical advantages in voice quality.

Objective: The objective of this study was to investigate the benefit of mobile Voice over Internet protocol (VoIP) over conventional mobile phone calls (Global System for Mobile Communications, GSM) on speech intelligibility and quality for cochlear implant (CI) recipients. Study Design: Cross-sectional, prospective. Setting: Tertiary referral center. Patients: A volunteer sample of experienced, German-speaking, adult CI recipients was considered. Volunteers with less than 50% aided monosyllabic word discrimination were excluded. Intervention: Smartphone communication was changed from GSM to VoIP on two separate devices (A and B). Main Outcome Measures: Speech intelligibility was assessed with the Hochmair-Shulz-Moser (HSM) test in noise, speech quality with the mean opinion score (MOS) survey and the perceptual evaluation of speech quality (PESQ) algorithm. Results: With device A, the mean HSM scores were 64.40% ± 32.41 with GSM and 77.28% ± 21.60 with VoIP (p = 0.0573). 66.7% of patients had a higher score with VoIP. For device B the means were 53.90% ± 21.77 and 69.07% ± 21.09 (p < 0.0001). 94.1% patients scored better with VoIP. With device A the average MOS scores were 3.12 ± 1.52 and 4.08 ± 0.95 (p = 0.0078). 76.9% of patients gave a higher score with VoIP. With device B the means were 2.71 ± 1.08 and 3.528 ± 1.44 (p = 0.0068). 56.3% of patients gave a higher score with VoIP. The effect was smaller when using an accessory cable. PESQ scores were significantly higher with VoIP (p < 0.001) in all configurations. Conclusions: CI recipients experience speech intelligibility and quality improvements using VoIP on a smartphone compared with conventional mobile phone calls.

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