28Hz

28Hz is a frequency that corresponds to 28 cycles per second. In the international system of units, it is expressed in hertz (Hz), the unit for frequency that denotes one oscillation per second. A value of 28 Hz falls within the lower range of audible sound, which typically spans from about 20 Hz to 20 kHz for healthy human hearing. At this frequency, many musicians and audio engineers refer to tones that are somewhat low, slightly below what is perceived as the lowest bass notes on most instruments.

The 28 Hz figure appears in several scientific and technical contexts. In acoustics research, researchers examine the effects of low‑frequency vibrations on building structures and on human perception. The sound wave at 28 Hz can produce noticeable physical vibrations, especially in resonant cavities or in musical instruments such as bass drums or tuned percussion.

In medical applications, 28 Hz is sometimes used as a therapeutic frequency in neuromodulation therapies, including certain forms of transcranial magnetic stimulation and vagal nerve stimulation protocols. Empirical studies have explored the influence of this frequency on brain rhythms, particularly within the theta band, typically defined between 4 Hz and 8 Hz, and its potential interaction with weaker signals in the 20–30 Hz range that may overlap with beta activity.

The frequency also displays relevance in electrical engineering, where low‑frequency periodicities can occur in power lines or signal generators. For instance, the line frequency in North America is 60 Hz; harmonics and intermodulation products occasionally introduce subharmonics such as 28 Hz in certain filter circuits.

Finally, 28 Hz is occasionally cited in multimedia contexts. Some video game developers use it as a background beat in rhythmic gameplay mechanics, leveraging its human perceptual capacity to create tension or a steady pulse. Note that while 28 Hz is technically perceptible, the subjective auditory experience varies among listeners.