Fundamental Frequency Explained: Role in Microphone Design and Audio Engineering

Content Summary

This article provides a systematic explanation of the definition, mathematical expression, measurement methods, and specific applications of fundamental frequency in real life and microphone systems from the professional perspective of a Microphone Manufacturer.

Drawing on the national standard GB/T 3947–1996 and incorporating content from publications such as “Detailed Explanation of Sound Power Level,” “Detailed Explanation of Sound Intensity Level,” and “Detailed Explanation of Microphone Frequency Response,” the paper delves into how fundamental frequency influences the sound pickup performance and audio quality of dynamic microphones, condenser microphones, and wireless microphones, helping readers build a comprehensive acoustic knowledge framework.

Fundamental Frequency: The Core Frequency of Sound and Its Critical Role in Microphone Design and Manufacturing

As a microphone factory and manufacturer with years of experience, we understand the importance of every detail in audio signals. In the research, development, and production of microphones, the “fundamental frequency” is one of the key factors determining pickup quality and sound reproduction.

According to the national standard GB/T 3947–1996, definition 2.61 states:

“The frequency of a sinusoidal quantity that is identical to the period in a periodic oscillation.”

Or: “The lowest natural frequency of a vibrating system.”

In other words, the fundamental frequency determines the basic pitch of a sound. Whether it is human voice, musical instruments, or environmental sound sources, they all have specific fundamental frequency distributions, which directly affect how a microphone “hears” and reproduces these sounds.

This article will delve into the definition, measurement methods, practical applications, and performance of the fundamental frequency in different types of microphones from the professional perspective of a microphone manufacturer. It will also combine content from “Detailed Explanation of Sound Power Level” “Detailed Explanation of Sound Intensity Level,” and “Detailed Explanation of Microphone Frequency Response,” this article will help you gain a more comprehensive understanding of this foundational yet critical concept in audio engineering.

1. What is the fundamental frequency? Why is it important?

1. The scientific definition of the fundamental frequency

The fundamental frequency (f₀) refers to the lowest frequency component in a periodic waveform and is the base frequency of that waveform.

National Standard GB/T 3947–1996, Definition 2.61, provides two descriptions:

In periodic oscillation, the frequency of the sine wave that aligns with the entire waveform period;

or, in a vibrating system, its lowest natural frequency;

This means:

If a sound exhibits periodic changes;

then its lowest frequency is the fundamental frequency;

Other higher frequencies are called harmonics, which are integer multiples of the fundamental frequency;

For example:

The fundamental frequency of adult male speech typically ranges from 85 Hz to 180 Hz;

For adult females, it ranges from 165 Hz to 255 Hz;

These frequencies constitute the “pitch” we perceive auditorily.

2. Mathematical expression of the fundamental frequency

The fundamental frequency can be calculated using the following formula:

f₀ = 1 / T

Where:

T is the time required for the signal to repeat once (unit: seconds)

The unit of f₀ is hertz (Hz)

Example:

If the period of a sine wave is 0.01 seconds;

then its fundamental frequency is 1 / 0.01 = 100 Hz;

This is one of the standard frequencies for the E string of a double bass;

This mathematical relationship is not only applicable to music theory but is also widely used in the design and calibration of audio equipment.

3. How to measure the fundamental frequency?

Common methods for detecting the fundamental frequency include:

Autocorrelation Method: Estimates the period by analyzing the temporal similarity of the signal;

Fast Fourier Transform (FFT): Converting the signal to the frequency domain to identify the strongest low-frequency components;

Cepstrum Analysis: Suitable for complex speech signals, effectively separating the fundamental frequency and harmonics;

These techniques are widely applied in speech recognition, automatic tuners, karaoke scoring systems, and other fields, and also serve as important reference indicators for microphone factory testing.

2. The Relationship Between Fundamental Frequency and Acoustic Parameters: Understanding Sound Energy Transmission from the Source

Although the fundamental frequency itself is a frequency parameter, it is closely related to the energy characteristics of sound. Understanding the fundamental frequency helps us gain a more comprehensive understanding of sound propagation paths, spatial distribution, and sound pickup effects.

1. Fundamental Frequency and Sound Power

Sound power describes the total energy emitted by a sound source. The fundamental frequency is the most basic frequency component of this energy.

For example:

The sound power output of a large loudspeaker system may reach several watts;

The low-frequency range (e.g., around 100 Hz) often contains a significant amount of fundamental frequency energy;

This gives sounds in this frequency range greater impact and penetration;

Therefore, when evaluating audio systems or recording environments, it is essential to consider the sound power level carried by the fundamental frequency to ensure that the equipment can withstand and accurately reproduce this energy.

2. Fundamental Frequency and Sound Intensity

Sound intensity indicates the flow of energy per unit area and has directionality. As the primary component of sound, the fundamental frequency directly influences changes in sound intensity.

For example:

At the center of the stage near the speakers;

fundamental frequency energy is concentrated, resulting in higher sound intensity;

while at the edges of the audience seating area, sound intensity decreases, leading to poorer low-frequency perception;

This explains why, when positioning microphones, it is essential to consider the directionality and spatial distribution of the fundamental frequency to achieve optimal sound pickup.

3. Fundamental Frequency and Frequency Response

Every microphone has a specific frequency response range. If the fundamental frequency of the recorded sound falls within an area where the microphone's response is weak, it may result in sound distortion or a dull, lackluster tone.

For example:

Dynamic microphones like the Mr Senma S-ONE have a frequency response range of approximately 50 Hz – 15 kHz;

They perform well with male voices that have a lower fundamental frequency;

However, they may be insufficient for female voices or violins with rich high-frequency overtones;

Therefore, it is essential to thoroughly understand the fundamental frequency distribution of the target sound source before recording to select the most suitable microphone model.

3. The Performance and Impact of Fundamental Frequency in Different Types of Microphones

As a professional microphone manufacturer, we fully consider the impact of fundamental frequency during the product design phase to ensure stable sound pickup and accurate sound reproduction across various application scenarios.

1. Dynamic Microphones

Dynamic microphones are robust and have strong noise-canceling capabilities, making them suitable for capturing sounds with abundant fundamental frequency energy.

Mr Senma S-ONE Dynamic Vocal microphone

For example:

Mr Senma S-ONE is commonly used for live performances;

it responds well to vocal fundamental frequencies (60 Hz – 16 kHz);

it is particularly suitable for speeches, podcasts, and similar scenarios;

this type of microphone is often used in high-sound-pressure environments, such as concerts and conference sound systems, due to its excellent durability and stable low-frequency response.

2. Condenser Microphones

Condenser microphones have high sensitivity and a wide frequency response, making them suitable for recording acoustic instruments with rich fundamental frequencies and overtones.

Mr Senma f22S large diaphragm condenser microphone

For example:

The Mr Senma F22s is used for vocal recording in studios;

It clearly reproduces low-frequency fundamental details;

It also preserves high-frequency overtones, making the sound more full-bodied;

Due to its high-fidelity capture of low-frequency fundamentals, the condenser microphone is the preferred choice for professional recording studios.

3. Wireless Microphones

Wireless microphones are commonly used in mobile settings such as interviews and speeches. When fundamental frequency energy is strong, it may cause compressors to trigger incorrectly or preamplifiers to overload.

Mr Senma P200 Dual Channel Professional Wireless Microphone

For example:

A speaker speaking close to a lavalier microphone;

Strong fundamental frequency energy;

May cause “plosive” sounds or distortion;

In such cases, using an anti-pop filter or adjusting the EQ can reduce the impact of low-frequency bands.

As manufacturers, we optimize the preamplifier circuitry and dynamic compression algorithms in wireless microphone designs to accommodate high fundamental frequency energy inputs, ensuring stable and reliable transmission performance.

4. Interaction between fundamental frequency and recording environment

In addition to the microphone itself, the recording environment also significantly influences fundamental frequency performance.

1. Room Resonance and Standing Wave Effects

The dimensions and shape of a room can enhance or attenuate certain frequencies. Especially in the low-frequency fundamental frequency range, room resonance is more likely to be triggered, causing a “rumbling” sensation or unbalanced tone.

For example:

A room with an unreasonable length-to-width ratio;

Standing waves may occur around 80 Hz;

Causing vocals or bass to sound muddy and unclear;

Therefore, in recording studio design, low-frequency control is often achieved through sound-absorbing materials, diffusion panels, and other methods.

2. Environmental Noise Masking Effect on Fundamental Frequencies

Background noise, especially low-frequency noise (such as from air conditioning or ventilation systems), can severely interfere with the clarity of fundamental frequencies.

For example:

In conference halls or podcast recordings;

If there is low-frequency humming noise;

even if the microphone performs well, it may still fail to clearly capture the speaker's fundamental frequency information;

By referencing “A Detailed Explanation of Microphone Sensitivity,” one can determine whether to select a microphone with strong directionality and good low-frequency suppression to enhance speech intelligibility.

5. The Importance of Fundamental Frequency from a Microphone Manufacturer's Perspective

Whether in speech recognition, music production, or live sound reinforcement, the fundamental frequency is a core factor determining sound quality and perceptual experience.

As a microphone factory specializing in the research, development, and production of audio equipment, we fully understand the impact of fundamental frequency on microphone selection, sound pickup performance, and final audio quality. By deeply understanding the definition, mathematical expression, measurement methods, and relationships between fundamental frequency and parameters such as sound power and sound intensity, we can better design and optimize products to meet the high-quality audio needs of different users.

Only by combining theory with practice can we truly achieve high-quality audio capture and transmission.