Why Temperature Can Lower the Pitch of a Guitar

Temperature has an affect on acoustic instruments; the guitar proves to be no exception to this rule. This explains why professionals recommend that you tune in the hall or concert arena before you play. A sound check helps to ensure that the guitar plays in tune with the rest of the instruments in the hall.

Intonation

When referring to the sound of a guitar, typically that refers to the timbre or the characteristic of the actual guitar sound. However, one component of sound referred to as intonation or pitch does have an effect and can be changed due to temperature fluctuations. Intonation affects the overall degree of highness or lowness of pitch. Musicians around the world have standardized pitch to A=440 hertz. This means frequencies vibrating at 440 cycles per second result in the pitch A. From that starting point, tuning the other pitches of an instrument becomes possible.

Warm Temperatures

When the temperature of the instrument or the air surrounding the instrument results in a heating of the instrument, the pitch or sound of the guitar will increase. When a pitch goes above the standard accepted frequency it is referred to as sharp. An instrument can be sharp to a small degree without the audience noticing. Since overtones, the unheard pitches that help to color the sounding pitches, ascend instead of descend, a sharp pitch doesn't stick out as much. This is good news for performers since the stage lights create large amounts of heat, raising the overall pitch of an ensemble during a performance.

Cold Temperatures

Cold temperatures lower the pitch of a guitar. This is more problematic because as a pitch goes below the minimum frequency it begins to sound dull and is easily recognizable by the audience. To prevent this, the performer generally tunes the instrument a little higher if the room is cold. This helps to prevent the tuning from dropping too low and keeps the instrument in a suitable pitch range. Orchestras and large ensembles generally tune the entire ensemble to A=444 hertz or higher to ensure that the pitch stays above a certain threshold.

Acoustic vs. Electric 

An acoustic guitar reflects changes more apparently than an electric guitar. The reason for this has to do with the manner that sound travels. In an acoustic guitar, the strings interact with the air around and inside the instrument. If the air turns cold, the air in the instrument will also be cold, lowering the pitch of the instrument. In an electric instrument, the sound travels electronically, so there is very little, and in most cases no, change in pitch.