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LOUDNESS AND PITCH

BY

EKIUGBO OGHENESUOWHO PHILIP FOA/07/08/131141

A TERM PAPER SUBMITTED TO MR. MOSES DARAH DEPARTMENT OF LANGUAGES AND LINGUISTICS DELTA STATE UNIVERSITY, ABRAKA-NIGERIA

IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE COURSE: INTRODUCTION TO ACOUSTIC PHONETICS

COURSE CODE: LLL 211

NOVEMBER 2009 INTRODUCTION We hear speech sounds in terms of four perceptual categories namely, loudness, pitch, quality and length. This write up shall be limited to the first two which are loudness and pitch. Loudness is an auditory property of a sound that enables a listener to place it on a scale going from soft to loud without considering the acoustic properties such as the intensity of the sound. Loudness is the correlate of stress (Stress is a suprasegmental feature of utterances. It is pronounced with a greater amount of energy) thus, stressed sounds tend to louder than unstressed one but the relationship is an utterance. Pitch is an auditory property of a sound that enable a listener to place it on a scale going from low to high without considering the acoustic properties such as the frequency of the sound.

THE ACOUSTIC PROPERTIES OF LOUDNESS AND PITCH The acoustic property of loudness is Intensity. This is simply the amount of acoustic energy that is present in the production of a sound. The loudness of a sound depends mainly on its acoustic intensity, thus when there is an increase in the amount of energy of a sound source, there is an increase in the loudness. “Acoustic intensity is proportional to the average size or amplitude of the variation in the air pressure” Ladefoged (1975:187). In fact the energy of a sound source depends on the amplitude of vibration….” Alec (1974) The acoustic property of pitch on the other hand is Frequency. This is the rate at which the vocal cords vibrate per second, or simply put, the timing of sound. The pitch of a sound depends on the rate of the vibration of the vocal cords. Each opening and closing of the vocal cords causes a peak of air pressure in the sound wave, thus, in a sound with a high pitch, there is a higher frequency of vibration than in a sound with a low pitch. In practice, when a speech sound goes up in frequency, it also goes up in pitch (though equal steps in increasing pitch do not produce the effect of equal steps in increasing pitch). For the most part, in an introductory level of the subject, the pitch of a sound may be equated with its fundamental frequency, and indeed, some books do not distinguish between the two terms, using pitch for both the auditory property and the physical attribute.

ACOUSTIC MEASUREMENT OF LOUDNESS AND PITCH One of the objectives of any science is to be able to measure the things that are being described so that they can be expressed in terms of valid, reliable and significant numbers. Loudness (Intensity) and Pitch (Frequency) can be calibrated with scales in Decibel (db) and Hertz (Hz) respectively.

VARIATION IN LOUDNESS AND PITCH We are a good deal less sensitive to differences of loudness than we are of pitch. Experiments have shown that at a given frequency, we can in ideal condition distinguish some 250 or more degrees of loudness of a pure tone, whereas at a fixed loudness, we may not be able to hear more than 1000 difference in pitch. The questions that now arise are: i.	What are the causes of these variations (differences/changes)? ii. What are the messages these variations passes across?

CAUSES Sounds has a greater sonority (the sonority of a sound is its loudness relative to that of other sounds with the same length, stress and pitch) due largely to its being produced with a greater mouth opening. Pitch variation is determined by several factors the most important of which is the tension of the vocal cords. If the vocal cords are stretched, the pitch of the sound will go up. Altering the of the vocal cords is the normal way of producing most of the pitch, in association with the variation in the position of the vocal cords in different phonation type, for example, creaky voice usually have a low pitch as well as a particular voice quality.

MESSAGES BEING PASSED ACROSS Many different kinds of information can be conveyed by variation in pitch. Some of this information simply indicates the personal characteristics of the speaker is the male or female, and to the same extent his or her age. In addition, it conveys a great deal of non-linguistic information about the speaker’s emotional state whether the person is calm or angry, happy or sad etc.

Pitch variation can determine the meaning of a word. For example, In Chinese, the consonant-vowel sequence [ma] produced with a high and low pitch means “mocker” but the same sequence produced with a high and falling pitch means “scold”. This phenomenal is known as tone. Pitch variation can also convey syntactic information, such is generally known as Intonation.

CONCLUSION Loudness and pitch are elements of acoustic phonetics whose properties are Intensity and Frequency, with Decibel and Hertz as acoustic measurement respectively.

REFERENCES Alec, N. 1974. The Use of Microphones…: Focal Press Limited. Ladefoged, P. 1975. A Course in Phonetics. USA: Harcourt Brace Jevanovich. O’Connor, J A. 1972. Phonetics. London: Penguim Books.