Golf swing analysis from pre-strike sound

1. A system, comprising:

a microphone that senses sound and in response outputs a sound signal indicative of the sound, wherein the sound signal includes an intensity of the sound over time;

a processor, coupled to the microphone to receive the sound signal, configured to analyze the sound signal to:

identify in the sound signal an impact of a golf club with a golf ball during a swing of the golf club; and

identify a time of impact based on a local maximum of the intensity that corresponds to a rate of change of the intensity transcending a threshold;

determine a characteristic of the swing of the golf club based on a portion of the sound signal corresponding to sound sensed, at least in part, before the impact, by applying a low pass filter and determine the characteristic of the swing from the sound signal corresponding to a predetermined time period ending at the time of impact; and

a user interface, coupled to the processor, configured to display information related to the characteristic of the swing as determined by the processor.

2. The system of claim 1 , wherein the sound signal includes an intensity of the sound over time and wherein the processor is further configured to:

identify a time of impact based on a local minimum of the intensity that corresponds to a rate of change of the intensity transcending a threshold; and

determine the characteristic of the swing from the portion of the sound signal corresponding to a predetermined time period ending at the time of impact.

3. The system of claim 2 , wherein the processor is further configured to determine the characteristic of the swing based on a sound pressure level of the portion of the sound signal during the predetermined time period.

4. The system of claim 1 , wherein the processor is further configured to determine the characteristic of the swing based on a sound pressure level of the sound signal, as filtered through the low pass filter having a cutoff of approximately 500 Hertz, during the predetermined time period.

5. The system of claim 1 , wherein the processor is further configured to determine the characteristic of the swing based on a peak frequency amplitude of the sound signal as filtered through the low pass filter having a cutoff of approximately 500 Hertz, during the predetermined time period.

6. The system of claim 1 , further comprising a mobile electronic device, wherein the microphone, the processor, and the user interface are components of the mobile electronic device.

7. The system of claim 1 , wherein the processor, in determining the characteristic of the golf club swing, determines a speed of at least a head of the golf club before the impact.

8. A method, comprising:

receiving, from a microphone, sound signal based on the sound sensed by the microphone, wherein the sound signal includes an intensity of the sound over time;

identifying, using one or more processors, in the sound signal obtained from a microphone, an impact of a golf club with a golf ball during a swing of the golf club;

identifying, with the one or more processors, a time of impact based on a local maximum of the intensity that corresponds to a rate of change of the intensity transcending a threshold;

determining, using the one or more processors, a characteristic of the swing of the golf club based on a portion of the sound signal corresponding to sound sensed, at least in part, before the impact, by applying a low pass filter and determine the characteristic of the swing from the sound signal corresponding to a predetermined time period ending at the time of impact; and

generating, using the one or more processors, a user interface to display information related to the characteristic of the swing as determined by the processor.

9. The method of claim 8 , wherein the sound signal includes an intensity of the sound over time and further comprising:

identifying, with the processor, a time of impact based on a local minimum of the intensity that corresponds to a rate of change of the intensity transcending a threshold; and

determining, with the processor, the characteristic of the swing from the portion of the sound signal corresponding to a predetermined time period ending at the time of impact.

10. The method of claim 9 , further comprising determining, with the processor, the characteristic of the swing based on a sound pressure level of the portion of the sound signal during the predetermined time period.

11. The method of claim 8 , wherein the sound signal includes an intensity of the sound over time and further comprising:

identifying, with the processor a time of impact based on a local maximum of the intensity that corresponds to a rate of change of the intensity transcending a threshold; and

determining, with the processor, the characteristic of the swing from the sound signal corresponding to a predetermined time period ending at the time of impact.

12. The method of claim 8 , wherein the characteristic is a speed of at least a head of the golf club before the impact.

13. The method of claim 8 , wherein the processor is further configured to determine the characteristic of the swing based on a sound pressure level of the sound signal, as filtered through the low pass filter having a cutoff of approximately 500 Hertz, during the predetermined time period.

14. The method of claim 8 , wherein determining the characteristic of the swing is based on a peak frequency amplitude of the sound signal as filtered through the low pass filter having a cutoff of approximately 500 Hertz, during the predetermined time period.