How to Test Your Speakers and Headphones With a Tone Generator
Before you spend hours mixing a track or diagnosing a sound problem, it helps to know exactly what your speakers or headphones are actually reproducing. A tone generator produces a pure, single-frequency signal — no room acoustics, no recording artifacts, just a clean test signal. This makes it much easier to hear what your equipment is and is not doing well.
Testing Frequency Response
Frequency response is how evenly your speakers or headphones reproduce different pitches. To test it, use a tone generator and slowly sweep from 20 Hz up to 20,000 Hz while listening. Ideally, the loudness should stay roughly constant across the range. In practice, you will hear the low end drop off as you go below the speaker's reach — this is the bass limit. You will also hear the high end either cut off or distort as you push past 15,000 Hz, depending on the quality of the driver. Budget headphones often have an artificially boosted mid-bass (around 100-200 Hz) that makes them sound "punchy" but masks detail. You can hear this clearly with a tone generator — the same perceived volume will be louder at bass frequencies than at mid-range frequencies.
Finding the Bass Limit
Start at 100 Hz and slowly decrease the frequency. At some point the tone will become noticeably quieter or disappear entirely — that is your speaker's bass limit. Most laptop speakers give up around 150-200 Hz. Good desktop speakers extend to 60-80 Hz. Subwoofers can go down to 20-30 Hz. Headphones vary widely: consumer earbuds often roll off below 50-60 Hz, while good over-ear headphones reach 20 Hz. Knowing your bass limit tells you whether you can trust your monitoring setup for low-end audio work.
Testing Channel Balance (Left vs Right)
Put on headphones and generate a tone at 1,000 Hz. It should appear to originate from the exact centre of your head — neither left nor right. If it sounds off-centre, you have a channel imbalance. This could be a hardware problem (one driver is louder) or a software issue (the OS or application has set an uneven balance). Next, check your audio settings — most operating systems have a balance control in the sound settings. A centred image at 1 kHz is the simplest test for confirming your stereo setup is working correctly. For speakers, the test is similar but stand or sit equidistant from both speakers.
Testing for Distortion
Generate a sine wave at high volume and listen carefully. A clean speaker will produce a smooth, pure tone — no buzzing, crackling, or rattling. Any of those sounds indicate distortion. Rattle often points to a loose part in the speaker enclosure. Buzzing can indicate a loose driver or a damaged voice coil. Crackling at only certain frequencies suggests the driver is struggling at its resonant frequency. Test at 50 Hz, 100 Hz, 200 Hz, 500 Hz, and 1,000 Hz — distortion often appears at only specific frequencies. If a speaker that used to be clean now rattles at a specific frequency, something has physically loosened.
Testing Your Hearing Range
A tone generator is also a quick way to check your personal hearing range. In a quiet room with headphones, start with the volume low — high-frequency tones can be uncomfortable and you may not notice how loud a tone is until it becomes audible. Generate a tone and slowly increase the frequency from 1,000 Hz upward. The standard upper limit for young adults is around 20,000 Hz, but this decreases with age — by age 40, many people cannot hear above 14,000-16,000 Hz. This is actually useful to know for audio work: if you cannot hear above 15,000 Hz, you may not be the best judge of whether a recording has excessive high-frequency harshness. Testing the low end is also informative: most people can feel rather than hear frequencies below 40-50 Hz, but the transition point varies.
Standard Test Frequencies Worth Knowing
A few reference frequencies are worth memorizing. 60 Hz is the hum frequency of AC power in North America (50 Hz in Europe, most of Asia and Australia) — if you hear a 60 Hz tone and it sounds exactly like the hum in your audio setup, you have a ground loop problem. 440 Hz is Concert A, the standard tuning reference for instruments. 1,000 Hz is the standard loudness reference used in audio equipment testing. 3,000 Hz is where human hearing is most sensitive and where spoken consonants live — critical for voice intelligibility. 10,000 Hz is the "air" frequency; boosting it on an equalizer adds brightness and shimmer to a mix.
Summary
A tone generator is a simple but powerful diagnostic tool. Spending five minutes testing your speakers or headphones with one before a critical listening session gives you a clear picture of what your equipment can and cannot do. The PCM Drop tone generator covers the full 20 Hz to 20,000 Hz range with sine, square, sawtooth and triangle waveforms, and works entirely in your browser with no installation.