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Somatic, auditory and cochlear communication system and method

Somatic, auditory and cochlear communication system and method description/claims

This application claims the benefit of U.S. Provisional Application No. 60/705,219, filed Aug. 3, 2005, which is incorporated by reference in its entirety.

1. Field of the Invention

The invention relates to somatic, auditory or cochlear communication to a user, and more particularly, to somatic, auditory or cochlear communication using phonemes.

2. Description of the Related Art

Phonemes are the speech sounds that form the words of a language, when used alone or when combined. More precisely, a phoneme is the smallest phonetic unit, or part of speech that distinguishes one word from another. Various nomenclatures have been developed to describe words in terms of their constituent phonemes. The nomenclature of the International Phonetic Association (IPA) will be used here. Unless otherwise noted, examples of speech, speech sounds, phonetic symbols, phonetic spellings, and conventional spellings will be with respect to an American dialect of English, hereto forth referred to simply as English. The principles can be extended to other languages.

FIG. 1 illustrates several exemplary plots 100 to introduce several spectral and temporal features of human speech through the examination of the English word, “fake”, 105, and its component phonemes. The phonetic spelling (per the IPA) of the English word, “fake”, 105, is “faik”, 110. In English, the word comprises three separate phonemes: the consonant, “f”, 142; the diphthong vowel, “ai”, 191; and the consonant, “k”, 107. Because phonemes are language and dialect dependent, an English speaker will hear “ai” as a single sound, “long A”, 191, a diphthong (a sound combining two vowel sounds), while speakers of other languages may hear two different vowels, “a”, 113, and “i”, 114, each a monophthong (a single vowel sound). The phoneme, “k”, 107, also comprises two parts: a short period of relative silence, 117; followed by the abrupt appearance of sound frequencies in a range of about 2500 to 7000 Hz, 118.

Spectral and temporal features of the individual phonemes are partially observable when viewing a plot of the waveform 140 of the spoken word. Here, pressure is shown on the vertical axis and time is shown on the horizontal axis. A spectrogram 120 reveals greater detail and structure. Here, frequency is shown on the vertical axis, time on the horizontal axis, and power is represented as a grey scale, with darker shades corresponding to higher power (sound intensity) levels. The consonants “f”, 142, and “k”, 107, primarily consist of sound frequencies above approximately 3000 Hz, while the vowel “ai”, 191, primarily consists of sound frequencies below approximately 3500 Hz. The highlighted areas of the spectrogram 132, 134, 138 reveal additional features of human speech.

An early portion of the phoneme “f”, 132, magnified in panel (A), 133, comprises sound frequencies predominantly above 3000 Hz. The distribution of power is irregular over time and frequency giving rise to a sound quality resembling rushing air, and creating the granular pattern on the spectrogram 132, 133.

The highlighted portion of the phoneme “ai”, 134, magnified in panel (B), 135, shows a bimodal distribution of relatively low sound frequencies. Characteristic of diphthongs, one or more dominant frequencies, called “formants”, shift in frequency over time. A portion 136 of panel (B), 135, magnified further in panel (D), 137, reveals a waxing and waning of power in all frequencies, a characteristic of the human voice. Unvoiced phonemes such as “f”, 142, 132, 133, and “k”, 107, 118, 138, 139, do not exhibit these cyclical amplitude fluctuations.

Some phonemes increase or decrease in power or intensity over their duration. This is evident in the highlighted portion of the phoneme “k”, 138, magnified in panel (C), 139. Here, sound energy decreases continually during a period of about 70 milliseconds.

Another important feature of human speech is the period of relative silence preceding some consonants. In the current example, the phoneme “k”, 107, comprises approximately 70 milliseconds of quiet 117 followed by the audible portion 118 of the phoneme “k”, 107. Without this period of relative silence, some phonemes, including “k” would be unintelligible. Also, intervals of relative silence or power shifts are important for syllabification.

FIG. 2 is a table 200 of American English phonemes 225 shown in three nomenclatures: the International Phonics Association (IPA), s{mpA (a phonetic spelling of SAMPA, the abbreviation for Speech Assessment Methods Phonetic Alphabet, a computer readable phonetic alphabet), and the Merriam Webster Online Dictionary (m-w). Examples 226 of each phoneme (bold underlined letters) as used in an American English word are provided, along with the manner 237 and place 247 of articulation 227.

The manner of articulation 237 refers primarily to the way in which the speech organs, such as the vocal cords, tongue, teeth, lips, nasal cavity, etc. are used. Plosives 201, 204, 207, 211, 214, 217 are consonants pronounced by completely closing the breath passage and then releasing air. Fricatives 242, 243, 244, 245, 250, 252, 253, 254, 255 are consonants pronounced by forcing the breath through a narrow opening. Between the plosives, and the fricatives are two affricates 224, 234 composite speech sounds that begin as a plosive and end as a fricative. Nasals 261, 264, 267 are consonants pronounced with breath escaping mainly through the nose rather than the mouth. Approximants 274, 275, 276, 271 are sounds produced while the airstream is barely disturbed by the tongue, lips, or other vocal organs. Vowels are speech sounds produced by the passage of air through the vocal tract, with relatively little obstruction, including the monoplithong vowels 280, 281, 282, 283, 284, 285, 286, 287, 288, 289 and the diphthong vowels 291, 292, 293, 294, 295.

The place of articulation 247 refers largely to the position of the tongue, teeth, and lips. Bilabials, are pronounced by bringing both lips into contact with each other or by rounding them. Labiodentals are pronounced with the upper teeth resting on the inside of the lower lip. Dentals are formed by placing the tongue against the back of the top front teeth. Alveolars are sounded with the tongue touching or close to the ridge behind the teeth of the upper jaw. Palato-alveolars are produced by raising the tongue to or near the forward-most portion of the hard palate. Palatals are produced by raising the tongue to or near the hard palate. Velars are spoken with the back of the tongue close to, or in contact with, the soft palate (velum).

Other speech characteristics 228 include voice, dominant sound frequencies above about 3000 Hz (3 kHz+), and stops. In English, eight phonemes comprise a period of relative silence followed by a period of relatively high sound energy. These phonemes, called stops 228 are the plosives and the affricates 201, 204, 207, 211, 214, 217, 224, 234. Stops are not recognizable from their audible portion alone. Recognition of these phonemes requires that they begin with silence. Phonemes may be voiced or unvoiced. For example, “b”, 211, is the voiced version of “p”, 201, and “z”, 254, is the voiced version of “s”, 244. Most English consonants, the plosives, affricates, and fricatives 201, 204, 207, 211, 214, 217, 224, 234, 242, 243, 244, 245, 250, 252, 253, 254, 255 comprise sound frequencies above 3000 Hz. In order for an individual to be able to discriminate between these phonemes, he/she must be able to hear their higher frequencies. Unvoiced phonemes 201, 204, 207, 224, 242, 243, 244, 245, 250 in particular tend to be dominated by the higher sound frequencies.

In another embodiment there is a method of transforming a sequence of symbols representing phonemes into a sequence of arrays of nerve stimuli, the method comprising establishing a correlation between each member of a phoneme symbol set and an assignment of one or more channels of a multi-electrode array, accessing a sequence of phonetic symbols corresponding to a message, and activating a sequence of one or more electrodes corresponding to each phonetic symbol of the message identified by the correlation. The phonetic symbols may belong to one of SAMPA, Kirshenbaum, or IPA Unicode digital character sets. The symbols may belong to the cmudict phoneme set. The correlation may be a one to one correlation. Activating a sequence of one or more electrodes may include an energizing period for each electrode, wherein the energizing period comprises a begin time parameter and an end time parameter. The begin time parameter may be representative of a time from an end of components of a previous energizing period of a particular electrode. The electrodes may be associated with a hearing prosthesis. The hearing prosthesis may comprise a cochlear implant.

In one embodiment there is a method of processing a sequence of spoken words into a sequence of sounds, the method comprising converting a sequence of spoken words into electrical signals, digitizing the electrical signals representative of the speech sounds, transforming the speech sounds into digital symbols representing corresponding phonemes, transforming the symbols representing the corresponding phonemes into sound representations, and transforming the sound representations into sounds.

Transforming the symbols representing the phonemes into sound representations may comprise accessing a data structure configured to map phonemes to sound representations, locating the symbols representing the corresponding phonemes in the data structure, and mapping the phonemes to sound representations. The method additionally may comprise creating the data structure, comprising identifying phonemes corresponding to a language used by a user of the method, establishing a set of allowed sound frequencies, generating a correspondence mapping the identified phonemes to the set of allowed sound frequencies such that each constituent phoneme of the identified phonemes is assigned a subset of one or more frequencies from the set of allowed sound frequencies, and mapping each constituent phoneme of the identified phonemes to a set of one or more sounds. Establishing a set of allowed sound frequencies may comprise selecting a set of sound frequencies that are in a hearing range of the user. Each sound of the set of one more sounds may comprise an initial frequency parameter. Each sound of the set of one more sounds may comprise a begin time parameter. The begin time parameter may be representative of a time from an end of components of a previous sound representation. Each sound of the set of one more sounds may comprise an end time parameter. Each sound of the set of one more sounds may comprise a power parameter. Each sound of the set of one more sounds may comprise a power shift parameter. Each sound of the set of one more sounds may comprise a frequency shift parameter. Each sound of the set of one more sounds may comprise a pulse rate parameter. Each sound of the set of one more sounds may comprise a duty cycle parameter.

• Provisional Patent
• Utility Patent

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