Frequency Generator

What is a Frequency Generator?

A frequency generator (also called a tone generator or signal generator) is an audio tool that produces pure tones at specific frequencies. Unlike complex sounds like music or speech that contain many frequencies simultaneously, a pure tone consists of a single frequency oscillating at a steady rate. This makes frequency generators invaluable for audio testing, speaker calibration, hearing tests, and scientific experiments involving sound.

The human hearing range spans from approximately 20 Hz (very low bass) to 20,000 Hz or 20 kHz (very high treble), though this upper limit decreases with age. This frequency generator covers the entire audible spectrum, allowing you to test your hearing, calibrate audio equipment, or experiment with different frequencies and waveforms to understand how sound works.

Understanding Waveforms

Sine Wave

A sine wave is the purest form of sound—a smooth, periodic oscillation containing only a single fundamental frequency with no harmonics or overtones. Musically, it sounds clean and flute-like. Sine waves are the building blocks of all complex sounds and are essential for precise audio testing and calibration. They're ideal for hearing tests, speaker testing, and scientific applications because of their purity and predictability.

Square Wave

A square wave alternates instantly between maximum positive and negative values, creating a harsh, hollow sound. It contains the fundamental frequency plus odd harmonics (3rd, 5th, 7th, etc.), giving it a distinctly "buzzy" or "harsh" character. Square waves are common in electronic music, synthesizers, and vintage video game sounds. They're also useful for testing transient response in audio systems.

Sawtooth Wave

A sawtooth wave rises linearly from minimum to maximum then drops instantly, or vice versa. It contains all harmonics (both even and odd), creating a bright, brassy, "buzzy" sound rich in overtones. Sawtooth waves are frequently used in subtractive synthesis for creating strings, brass, and aggressive bass sounds. They provide the fullest harmonic spectrum of all basic waveforms, making them excellent starting points for sound design.

Triangle Wave

A triangle wave rises and falls linearly in a symmetric pattern. Like square waves, it contains only odd harmonics, but they fall off more rapidly, resulting in a softer, more mellow sound compared to square or sawtooth waves. Triangle waves sound somewhat hollow but gentler than square waves, making them useful for creating woodwind-like tones and softer synthetic sounds.

How to Use This Frequency Generator

1. Select your frequency: Use the slider, number input, or quick select buttons to choose a frequency between 20 Hz and 20,000 Hz. Common test frequencies are 100 Hz, 440 Hz (A4), 1 kHz, and 10 kHz.
2. Choose a waveform: Click one of the four waveform types. Sine is the most common for general testing. Square, sawtooth, and triangle are useful for specific applications or experimentation.
3. Adjust volume: Set the volume slider to a comfortable listening level. Always start low and increase gradually to avoid hearing damage.
4. Start the tone: Click "Start Tone" to begin generating the frequency. You can adjust frequency, waveform, and volume while the tone is playing.
5. Listen carefully: Use headphones or quality speakers for best results. Very low frequencies (below 80 Hz) require good bass response to be audible. Very high frequencies (above 15 kHz) may not be audible depending on your age and hearing health.
6. Stop when finished: Click "Stop Tone" to end playback. Never listen to loud test tones for extended periods.

Common Applications

Speaker & Headphone Testing

Sweep through different frequencies to test how well your speakers or headphones reproduce various parts of the audio spectrum. Quality audio systems should reproduce all frequencies relatively evenly. If certain frequency ranges sound much louder or quieter, it indicates frequency response issues. Test low frequencies (40-80 Hz) to check bass response, midrange (200-2000 Hz) for vocals and instruments, and high frequencies (5-15 kHz) for clarity and detail.

Hearing Tests

Test your hearing range by playing progressively higher frequencies. Most adults can hear up to 15-17 kHz, but this decreases with age and exposure to loud sounds. Children and teenagers often hear up to 20 kHz. If you can't hear above 12 kHz, consider protecting your hearing more carefully. Remember, inability to hear high frequencies is normal with age but can also indicate hearing damage.

Room Acoustics & Resonance Testing

Play different frequencies to identify room resonances (frequencies that sound unusually loud due to room dimensions and reflections). Rooms have "modes" where certain frequencies are amplified or cancelled due to standing waves. Finding these problematic frequencies helps with acoustic treatment placement and subwoofer positioning.

Audio Equipment Calibration

Use 1 kHz sine wave as a standard reference tone for calibrating audio levels in recording and broadcast equipment. Many professional standards use 1 kHz at -20dBFS or -18dBFS as the reference level for setting gain staging and metering.

Tinnitus Masking

Some people find that generating a tone near their tinnitus frequency provides relief through a masking effect. If you experience ringing in your ears, try different frequencies to find one that matches or masks the ringing. Consult a hearing specialist for proper tinnitus management.

Musical Reference (A440)

440 Hz is the standard tuning reference pitch for musical instruments, corresponding to the note A above middle C (A4). Musicians and vocalists can use this as a tuning reference when a dedicated tuner isn't available, though the chromatic tuner tool on this site is better suited for instrument tuning.

Sound Experiments & Education

Experiment with different frequencies and waveforms to learn how sound works. Observe how lower frequencies feel more physical, how high frequencies are more directional, and how different waveforms create different timbres from the same fundamental frequency. Great for students and anyone curious about acoustics.

Frequency Reference Guide

Sub-Bass (20-60 Hz)

Felt more than heard. Provides rumble and power in music and movies. Requires specialized subwoofers. Most small speakers cannot reproduce these frequencies.

Bass (60-250 Hz)

Fundamental frequencies of bass guitars, bass drums, and low male vocals. Essential for warmth and fullness in music. 100 Hz is a common test frequency for this range.

Low Midrange (250-500 Hz)

Contains body and warmth for many instruments and vocals. Excessive energy here can make mixes sound "muddy." Important range for snare drums, guitars, and lower male vocals.

Midrange (500-2000 Hz)

The most critical range for speech intelligibility and musical clarity. Human ears are most sensitive here. Contains fundamental and important harmonics of most vocals and instruments.

Upper Midrange (2-4 kHz)

Adds presence and definition to vocals and lead instruments. Can cause listening fatigue if too prominent. Critical for speech clarity—especially consonants.

Presence (4-6 kHz)

Adds clarity, detail, and "presence" to sound. Can make vocals and instruments sound closer and more intimate. Overemphasis can sound harsh or fatiguing.

Brilliance (6-20 kHz)

Contains the "air" and "sparkle" of sounds. Cymbals, breath sounds, and subtle details live here. The upper limit of human hearing decreases with age—teenagers can often hear 18-20 kHz, while many adults lose sensitivity above 15 kHz.

Safety & Best Practices

• Start at low volumes: Always begin with the volume slider at a low level and gradually increase. Sudden loud tones can damage hearing and startle you.
• Limit exposure time: Don't listen to loud test tones for extended periods. Even at moderate volumes, prolonged exposure to pure tones can cause temporary threshold shifts or fatigue.
• Protect your hearing: If testing high volumes for equipment purposes, take frequent breaks and consider using hearing protection. Your hearing cannot regenerate—damage is permanent.
• Be cautious with extreme frequencies: Very low frequencies (below 40 Hz) at high volumes can damage speakers, especially small ones. Very high frequencies (above 15 kHz) can be played louder than they sound, potentially causing hearing damage.
• Test responsibly: High frequencies can be especially annoying to others nearby, particularly young people and pets who may hear frequencies you cannot. Be considerate.
• Stop if uncomfortable: If you experience discomfort, dizziness, headache, or ear pain, stop immediately and lower the volume. Some people are sensitive to certain frequencies.

Technical Information

This frequency generator uses the Web Audio API's OscillatorNode to create mathematically perfect waveforms at your specified frequency. The oscillator runs at your device's native sample rate (typically 44.1 kHz or 48 kHz), ensuring accurate frequency reproduction across the entire audible spectrum.

Frequency accuracy is determined by the sample rate and is precise to within a fraction of a Hertz for all practical purposes. The oscillator generates continuous waveforms in real-time with no clicks or pops when starting or stopping (thanks to gain ramping). Volume control uses an exponential curve to match human perception of loudness. All processing happens locally in your browser—no data is transmitted.