Speech Sound

1. What Is Speech Sound?

Speech sound is the sound produced by the human voice when people talk.

When we speak, our body creates sound by moving air from the lungs through the vocal cords and shaping that sound with the mouth, tongue, teeth, lips, and nose.

Speech sounds are used to form:

Letters
Syllables
Words
Sentences
Conversations

Speech sound is important because it allows humans to communicate ideas, emotions, questions, and information.

2. How Speech Sound Is Produced

Speech begins with air. The basic process is:

Air moves out of the lungs.
The air passes through the vocal cords in the larynx.
The vocal cords may vibrate to create sound.
The throat, mouth, tongue, lips, teeth, and nose shape the sound.
The shaped sound becomes speech.

This process is called speech production.

3. Main Parts Used in Speech

Body Part	Role in Speech
Lungs	Push air upward to begin speech.
Diaphragm	Helps control breathing and airflow.
Larynx	Contains the vocal cords.
Vocal cords	Vibrate to create voiced sounds.
Tongue	Shapes many speech sounds.
Lips	Help form sounds such as /p/, /b/, and /m/.
Teeth	Help form sounds such as /f/, /v/, and /th/.
Nose	Allows air to pass through for nasal sounds.
Mouth	Main space where speech sounds are shaped.

4. Voiced and Voiceless Sounds

Speech sounds can be grouped into voiced and voiceless sounds.

Voiced Sounds

A voiced sound happens when the vocal cords vibrate.

Examples of voiced sounds include:

/b/
/d/
/g/
/v/
/z/
/m/
/n/

Voiceless Sounds

A voiceless sound happens when the vocal cords do not vibrate.

Examples of voiceless sounds include:

/p/
/t/
/k/
/f/
/s/
/h/

Try it:
Place your fingers gently on your throat and say:

“zzzz” — you should feel vibration.
“ssss” — you should not feel much vibration.

5. Vowels

Vowels are speech sounds made when air flows freely through the mouth.

The letters usually associated with vowels are:

A
E
I
O
U

Sometimes Y acts like a vowel.

Examples of vowel sounds:

/a/ as in cat
/e/ as in bed
/i/ as in sit
/o/ as in hot
/u/ as in cup

Vowels are important because they usually form the center of a syllable.

6. Consonants

Consonants are speech sounds made when airflow is partly or completely blocked.

The blockage can happen with the:

Lips
Tongue
Teeth
Roof of the mouth
Throat

Examples:

/p/ uses the lips.
/t/ uses the tongue near the teeth.
/k/ uses the back of the tongue.
/f/ uses the teeth and lower lip.
/s/ uses a narrow space for air to pass through.

7. Place of Articulation

The place of articulation is where in the mouth or throat a speech sound is made.

Place of Articulation	Description	Example Sounds
Bilabial	Both lips come together.	/p/, /b/, /m/
Labiodental	Lower lip touches upper teeth.	/f/, /v/
Dental	Tongue touches or nears teeth.	/th/
Alveolar	Tongue touches ridge behind teeth.	/t/, /d/, /s/, /z/, /n/
Velar	Back of tongue touches soft palate.	/k/, /g/
Glottal	Sound made at the vocal cords.	/h/

8. Manner of Articulation

The manner of articulation describes how airflow is controlled when making a sound.

Manner	Description	Example Sounds
Stop	Air is completely blocked, then released.	/p/, /b/, /t/, /d/, /k/, /g/
Fricative	Air is forced through a narrow opening.	/f/, /v/, /s/, /z/, /sh/
Nasal	Air flows through the nose.	/m/, /n/
Affricate	Begins like a stop and ends like a fricative.	/ch/, /j/
Liquid	Smooth flowing sound.	/l/, /r/
Glide	Quick vowel-like sound.	/w/, /y/

9. Phonemes

A phoneme is the smallest unit of sound that can change the meaning of a word.

Example:
The words bat and pat differ by only one sound: /b/ and /p/. Because the meaning changes, /b/ and /p/ are different phonemes in English.

Word Pair	Changing Sound
cat / bat	/c/ and /b/
sit / sat	/i/ and /a/
fan / van	/f/ and /v/
sip / zip	/s/ and /z/

10. Syllables

A syllable is a beat or unit of sound in a word. Most syllables contain a vowel sound.

Word	Number of Syllables
cat	1
tiger	2
computer	3
communication	5

Syllables help organize speech into smaller parts.

11. Pitch in Speech

Pitch is how high or low a voice sounds. Pitch depends on how fast the vocal cords vibrate.

Faster vibration creates higher pitch.
Slower vibration creates lower pitch.

People use pitch to show meaning and emotion.

A rising pitch can signal a question.
A lower pitch can sound serious.
A changing pitch can show excitement.

12. Loudness in Speech

Loudness is how strong or quiet a speech sound is. Loudness depends on the amount of air pressure used when speaking.

Whispering uses low loudness.
Speaking normally uses medium loudness.
Shouting uses high loudness.

Loudness can help show emotion, urgency, or emphasis.

13. Speech Rate

Speech rate is how fast or slow someone talks.

A fast speech rate can show excitement, nervousness, or urgency.
A slow speech rate can help make information easier to understand.

Good speakers often adjust their speech rate depending on the situation.

14. Stress and Emphasis

Stress means saying part of a word or sentence more strongly than the rest. Stress can change meaning.

Example Sentence:
“I didn’t say he stole the book.”

Depending on which word is stressed, the sentence can have different meanings:

I didn’t say he stole the book.
I didn’t say he stole the book.
I didn’t say he stole the book.
I didn’t say he stole the book.

Stress helps listeners understand what information is most important.

15. Intonation

Intonation is the rise and fall of pitch during speech. Intonation helps communicate meaning, mood, and sentence type.

Intonation Pattern	Common Meaning
Rising pitch	Question or uncertainty
Falling pitch	Statement or command
Changing pitch	Emotion or emphasis

Example:
“You’re coming.” sounds like a statement.
“You’re coming?” sounds like a question.

16. Speech Sound and Technology

Computers can record, analyze, and recognize speech sounds.

Speech technology is used in:

Voice assistants
Speech-to-text tools
Translation apps
Automated phone systems
Captioning software
Security systems
Hearing aids
Language-learning apps

To process speech, computers analyze features such as:

Frequency
Pitch
Loudness
Timing
Pauses
Patterns of sound

17. Speech Recognition

Speech recognition is when a computer converts spoken words into text or commands.

Examples:

Saying “Call Mom” to a phone
Using voice typing in Google Docs
Asking a smart speaker a question
Dictating a message

Speech recognition systems must handle challenges such as:

Accents
Background noise
Different speaking speeds
Similar-sounding words
Multiple speakers
Unclear pronunciation

18. Speech Sound in Digital Form

When speech is recorded by a computer, it is converted into digital data.

The process usually includes:

A microphone captures the speech sound.
The sound becomes an electrical signal.
The signal is sampled many times per second.
Each sample is stored as a number.
The numbers are saved in an audio file.

Digital speech can then be edited, stored, transmitted, or analyzed.

19. Spectrograms

A spectrogram is a visual representation of sound. It shows how frequencies change over time.

A spectrogram usually shows:

Time on the horizontal axis
Frequency on the vertical axis
Intensity or loudness using color or brightness

Speech scientists and computers use spectrograms to study speech patterns.

Spectrograms can help identify:

Vowels
Consonants
Pitch changes
Pauses
Noise
Speaker differences

20. Why Speech Sound Matters

Understanding speech sound is useful in many fields.

Field	Use of Speech Sound
Computer Science	Speech recognition and AI assistants
Medicine	Speech therapy and hearing tests
Education	Reading, language learning, and communication
Music	Singing and vocal performance
Forensics	Voice analysis and speaker identification
Engineering	Audio systems and noise reduction
Accessibility	Captions, dictation, and assistive technology

21. Key Vocabulary

Term	Meaning
Speech sound	Sound made by the human voice to communicate.
Speech production	Process of creating speech sounds.
Vocal cords	Tissue in the larynx that vibrates to create voiced sounds.
Voiced sound	Sound made with vocal cord vibration.
Voiceless sound	Sound made without vocal cord vibration.
Vowel	Speech sound made with open airflow.
Consonant	Speech sound made with blocked or restricted airflow.
Place of articulation	Where a sound is made in the mouth or throat.
Manner of articulation	How airflow is controlled when making a sound.
Phoneme	Smallest sound unit that can change word meaning.
Syllable	Beat or unit of sound in a word.
Pitch	How high or low a voice sounds.
Loudness	How strong or quiet a sound is.
Speech rate	Speed of speaking.
Stress	Extra emphasis placed on a sound, syllable, or word.
Intonation	Rise and fall of pitch in speech.
Spectrogram	Visual display of sound frequencies over time.
Speech recognition	Technology that converts spoken words into text or commands.

22. Main Ideas to Remember

Speech sound is created by air, vocal cords, and the movement of the mouth.
Vowels are made with open airflow.
Consonants are made by blocking or restricting airflow.
Speech sounds can be voiced or voiceless.
Phonemes are the smallest sound units that can change meaning.
Pitch, loudness, rate, stress, and intonation affect how speech sounds.
Computers can digitize, analyze, and recognize speech.
Speech sound is important in communication, computer science, medicine, education, and accessibility.

Class Notes for High School Students