Sound(slight Christmas theme)

3. Distance between wave crests, longer in a tuba's low Christmas horn blast than a flute's tweet, inverse to frequency (10)
8. Bouncing back of sound waves, creating echoes in a harp's resonant chamber during a yuletide melody, law of angles (10)
9. How often waves hit per second, like the rapid jingle of Santa's sleigh bells on a violin string, measured in Hertz (9)
10. Squeezed part of a sound wave, denser like crowded shoppers hearing mall Santa's bell, opposite of rarefaction (11)
12. Sound reflection that might bounce back your "Ho ho ho!" in a snowy canyon, like a guitar amp feedback, needs a surface (4)
14. Back-and-forth motion creating sound, as in a guitar string strumming "Silent Night", what starts all waves (9)
15. Unit for sound intensity, whispering "Merry Christmas" is about 20, while a rock concert drum is 110, logarithmic scale (7)

1. This wave property determines if your drum solo during "Little Drummer Boy" is a bang or a whisper, it's the max displacement (9)
2. When vibrations match and amplify, like a wine glass singing with a festive flute note, causes big shakes (9)
4. High-frequency waves beyond hearing, used in scans but imagine Santa's elves using it for reindeer check-ups, above 20 kHz (10)
5. Loudness level, cranked up for trumpet fanfares in "Joy to the World", linked to amplitude (6)
6. Material sound travels through, like air for carol singers or water for underwater sleigh bells, vacuum says no (6)
7. Quality that makes a violin sound different from a clarinet playing the same carol note, it's the tone color (6)
11. How high or low a note sounds, like a piccolo's shrill vs. a bass drum's boom in a holiday band, depends on frequency (5)
13. Repeated swinging motion, like a pendulum in a cuckoo clock chiming midnight on Christmas Eve, basis of waves (11)