A golf club set includes various types of clubs for use in different conditions or circumstances in which a ball is hit during a golf game. A set of clubs typically includes a driver for hitting the ball the longest distance on a course. Fairway woods, rescue clubs, and hybrid clubs can be used for hitting the ball shorter distances than the driver. A set of irons are used for hitting the ball within a range of distances typically shorter than the driver or woods.
Designers and manufacturers of wood-type golf club heads (e.g., drivers, fairway woods, rescue clubs, hybrid clubs, etc.) have sought to find mass savings opportunities within the club head structure. Discretionary mass generally refers to the mass of material that can be removed from various structures providing mass. In some cases, the mass is removed for the purpose of reducing overall club mass to allow for higher club head speeds. In other cases, the removed mass can be distributed elsewhere to other structures within the golf club head to achieve desired mass properties, or to allow for the addition of adjustability features which typically add mass to the club head.
The acoustical properties of golf club heads, e.g., the sound a golf club head generates upon impact with a golf ball, affect the overall feel of a golf club by providing instant auditory feedback to the user of the club. For example, the auditory feedback can affect the feel of the club by providing an indication as to how well the golf ball was struck by the club, thereby promoting user confidence in the club and himself.
The sound generated by a golf club head is based on the rate, or frequency, at which the golf club head vibrates upon impact with the golf ball. Generally, for wood-type golf clubs (as distinguished from iron-type golf clubs), particularly those made of steel or titanium alloys, a desired frequency is generally around 3,000 Hz and preferably greater than 3,200 Hz. A frequency less than 3,000 Hz may result in negative auditory feedback and thus a golf club with an undesirable feel.
Accordingly, it would be desirable to provide wood-type golf club heads having features that provide mass savings and opportunities to provide discretionary mass. It would also be desirable to increase the vibration frequencies of golf club heads having relatively large volumes, relatively thin walls, and other frequency reducing features in order to provide a golf club head that provides desirable feel through positive auditory feedback but without sacrificing the head's performance.