When we speak, our vocal cords vibrate to create sound. Through analyzing different physical elements of speech, we are able to understand how and where sounds are made when we talk. One important part of speech is the fundamental frequency. Keep on reading to find out more about fundamental frequency in linguistics, including a definition, some examples, and some facts about the frequencies of our voices! We will also explore the relationship between fundamental frequency, pitch, and harmonics.
Fundamental Frequency Linguistics
In linguistics, fundamental frequency is an aspect of acoustic phonetics. So what is acoustic phonetics?
Acoustic phonetics refers to the study of the physical properties of speech. It is used to analyze sound wave signals in speech through a range of different frequencies, durations, and intensities.
In case you weren't aware, sound waves look like squiggly lines that fluctuate over time. Here's an example of how a sound wave fluctuates:
Fig. 1 - Sound waves are created when an object vibrates, such as the vocal cords.
Now let's focus on the definition of fundamental frequency:
Definition of Fundamental Frequency
Check out the definition of fundamental frequency below:
Fundamental frequency refers to the number of times per second our vocal cords vibrate when making voiced sounds.
As the name suggests, voiced sounds refer to sounds that make use of our vocal cords. All vowel sounds are voiced, but not all consonants are. Some consonant sounds, such as /p/, /f/ and /s/ are unvoiced. This means the vocal cords do not vibrate when producing these sounds.
Fundamental frequency is often abbreviated to F0.
Voice Fundamental Frequency
Have you ever wondered what the fundamental frequency of the human voice is? Well, this depends on the sex of the person, as most men tend to have naturally lower voices than women. The unit of frequency used to measure the fundamental frequency of sounds is Hertz, represented by the symbol "Hz."
DID YOU KNOW? Hertz is named after the German physicist Heinrich Hertz, who greatly contributed to the study of electromagnetism.
The fundamental frequency for men's voices is around 85-155 Hz, but there may be exceptions. For women, the fundamental frequency is around 165-225 Hz (typically an octave higher). For children, it is around 300 Hz.
What are the most important frequencies for speech sounds?
Most people can normally hear frequencies between 32 and 32000 Hz at intensities of 10 decibels (dB) and louder. The most important frequencies for speech sounds are between 250 and 8000 Hz.
Fundamental Frequency Example
Now let's take a look at an example of fundamental frequency. Below is a visual representation of a sound wave:
Fig. 2 - Fundamental frequency is measured in Hertz (Hz).
This particular sound wave has a fundamental frequency of 93 Hz.
In everyday conversations, the fundamental frequency of speech fluctuates to reflect our speech patterns. Fundamental frequency also changes depending on a person's sex and age. Because of this, fundamental frequency is unique to an individual and it is difficult to determine the exact range of frequencies that everyone adheres to in everyday conversations. You may find that different research will give different numbers. For example, below is a table containing the average fundamental frequencies of both males and females, from infancy to adulthood:
| Age | Female Frequency | Male Frequency |
| Infant | 440-590 Hz | 440-590 Hz |
| 3 | 255-360 Hz | 255-360 Hz |
| 8 | 215-300 Hz | 210-295 Hz |
| 12 | 200-280 Hz | 195-275 Hz |
| 15 | 185-260 Hz | 135-205 Hz |
| Adult | 175-245 Hz | 105-160 Hz |
Notice how the range of numbers in adulthood differ from those mentioned in the above section about voice fundamental frequencies? The only consistent observation that can be made is the fact that our fundamental frequencies get lower as we get older, and from the age of 8 onwards, men typically have lower fundamental frequencies than women.
Fundamental Frequency and Pitch: Meaning
Fundamental frequency is closely correlated with pitch. Are these two terms synonymous, or are there differences between them?
Although some may think that fundamental frequency is just a fancy word for pitch, others argue that pitch is a different concept. In fact, pitch is more to do with a person's perception of a fundamental frequency. In other words, fundamental frequency refers to the actual physical properties of a sound wave signal, whereas pitch refers to how our ears and brains perceive the signal regarding the rate of frequency.
In speech, we often alter the pitch of our voices to express different emotions. For example:
To show happiness or excitement, we tend to raise the pitch of our voice. On the other hand, to show sadness or disappointment, we often lower the pitch of our voice.
We also change the pitch of our voices to differentiate between different grammatical sentence functions. For example:
To express an interrogative (a question), we raise the pitch of our voice at the end of an utterance.
When we use a declarative sentence (ordering someone to do something), we tend to keep the pitch of our voice steady.
Have you ever noticed that some people raise the pitch of their voice - or increase the variation in pitch - when talking to babies? This is often referred to as "baby talk," and it has been suggested that altering the way we speak in this way helps babies to learn sound patterns in speech!
Fundamental Frequency and Harmonics
Both fundamental frequency and harmonics are physical properties of speech and are related to each other. Almost all signals contain harmonic frequencies. Let's take a look at the meaning of a harmonic:
A harmonic is a wave or signal whose frequency is a whole multiple of the fundamental frequency. For example, if the fundamental frequency of something is 100 Hz, the harmonics would be 200 Hz, 300 Hz, 400 Hz, etc. The fundamental frequency is the lowest value and is often referred to as the "first harmonic."
As well as in physics, harmonics are often associated with music. In music, harmonics are used to play higher notes on instruments, such as string and wind instruments.
Fundamental Frequency - Key takeaways
- Fundamental frequency is an aspect of acoustic phonetics, which is the study of the physical properties of speech.
- Fundamental frequency refers to the number of times per second our vocal cords vibrate when making voiced sounds.
The unit of frequency used to measure the fundamental frequency of sounds is Hertz, represented by the symbol "Hz."
Fundamental frequency refers to the actual physical properties of a sound wave signal, whereas pitch refers to how our ears and brains perceive the signal regarding the rate of frequency.
A harmonic is a wave or signal whose frequency is a whole multiple of the fundamental frequency.
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