Oto-Laryngologica. 2003 Vol 123(2) ; 219-222. **Section 2**

**Speech Processing Strategies** 

36 Cochlear Implant Research Updates

[13] Kronenberg J.,Migirov L.The role of mastoidectomy in cochlear implant surgery. Acta

**3** 

**Wavelet Based Speech Strategy in** 

A significant percentage of the populations in developed countries encounter hearing impairment. Cochlear Implant was developed to increase the hearing capacity of these people. In recent years, adults and children have benefited from the usage of Cochlear Implant and the users were positively affected by the improvement of implant techniques. Although these devices allow for increased performance, a significant gap still remains in speech recognition between Cochlear Implant user and people, who possess normal

The Cochlear implant prosthesis, works with direct stimulation of the auditory nerve cells of deaf people, whose recipient cells in their cochlea were destroyed (House&Berliner, 1982; House&Urban, 1979; Christiansen&Leigh, 2002; Loeb, 1990; Parkins&Anderson, 1983; Wilson, 1993). The system basically consists of the following sections; microphone, speech processor, transmitter, receiver and electrode array. Mainly, implant stimulation systems, signal processing strategies and techniques in increasing the suitability of the instrument to various patients were the improved upon this prosthesis. However, new developments in this area also exist on the configuration of hearing function, especially signal processing strategies.

Speech processing techniques are very important in increasing the users' hearing potential (Eddington, 1980; Wilson et al., 1991; Dormon et al., 1997; Moore&Teagle, 2002). A variety of strategies were developed in the recent years with the aim to improve the hearing abilities of deaf people and take these abilities closer to those of people with natural hearing. Of these, various speech processing strategies were developed for multi-channel cochlear implants (Derbel et al., 1994; Cheikhrouhou et al., 2004; Gopalakrishna et al., 2010; Millar et al., 1984). These strategies can be classified mainly in three parts; waveform strategies, feature

Wavelet method is a basic method that is used for noise filtering, compression and analysis of nonstationary signals and images. The wavelet transform is an appropriate method for semistationary signals and provides a good resolution in both time and frequency. Several studies were carried out on the use of the wavelet transform for speech processing. The wavelet transform gives better results than traditional methods in improving speech. The wavelet packet transform is a type of the discrete wavelet transform that allows for subband analysis in the second decomposition without any constraints. Basically, the wavelet packet

extraction strategies and hybrid strategy (N-of-M strategy).

**1. Introduction** 

listening capabilities.

**Cochlear Implant** 

Gulden Kokturk *Dokuz Eylul University* 

*Turkey* 
