RingMute

RingMute (Patent Ring mute 20040261602 via Google.com) is an acoustic foam ring with a flexible protective outer adhesive strip. The purpose of the RingMute is to darken and dampen the sound of a brass musical instrument using sound absorption technology. Attachment of the RingMute to a brass musical instrument is accomplished by fitting the bell rim into an incision located at the inner portion of the foam ring. Used mainly on trumpet, the RingMute is unique in that except for dampening and slightly darkening the sound, the trumpet maintains an unmuted sound when compared to internal mutes such as the Harmon, straight, or cup mutes and, external mutes such as the bucket and derby. The function of the acoustic ring is to absorb some of the frequencies at the bell where the highest frequencies are emitted. For a better understanding of bell acoustics see (Brass Instrument (lip reed) acoustics: an introduction, Effects of the Bell). The purpose of the flexible outer adhesive strip is to protect and support the fragile acoustic foam ring.

A device similar in effect is the Crown Royal cloth bag which attaches to the bell by placing the bell inside the cloth bag. Both RingMute and Crown Royal cloth bag are known for their dampening and darkening effect and are often used by jazz musicians to create an unbright darker tone.