The use of air horns at the ballpark can be traced back to Hilda Chester who popularized the idea of fans making themselves heard. During the 1930's when she would attend games at Ebbets Field with a frying pan and an iron ladle. The frying pan was soon replaced by her trademark brass cowbell. The idea quickly took hold throughout the USA and while the cowbell continues to enjoy regional popularity, popular culture has chosen the loud blast of an sounder as its successor. Modern day sounders often are adjustable up to 120db that when combined with the acoustics of a basketball or baseball stadium can be clearly heard on the field, in the dugouts, and in the broadcast booth. Here are the best canister available on the net.

High Tone Aerosol Air Horn for Sports Parties Safety Super Loud Noise Maker
High Tone Aerosol Air Horn for Sports Parties Safety Super Loud Noise Maker
$6.75
Time Remaining: 22d 8h 55m
Buy It Now for only: $6.75

1PC air horn Portable hand held security safety Party Sports LOUD BLAST 81OZ
1PC air horn Portable hand held security safety Party Sports LOUD BLAST 81OZ
$5.00
Time Remaining: 27d 1h 10m
Buy It Now for only: $5.00

2 air horn Portable hand held security safety Party Sports boat LOUD BLAST 81OZ
2 air horn Portable hand held security safety Party Sports boat LOUD BLAST 81OZ
$7.95
Time Remaining: 21d 3h 2m
Buy It Now for only: $7.95

MOTORCYCLE AIR HORN Stebel Nautilus Black UTV ATV Power Sports
MOTORCYCLE AIR HORN Stebel Nautilus Black UTV ATV Power Sports
$16.99
Time Remaining: 14d 6h 28m
Buy It Now for only: $16.99

MARINE SPORTS Air Horn Mini 14 oz Non Flamable 120 Decibel Vol USCG APPROVED
MARINE SPORTS Air Horn Mini 14 oz Non Flamable 120 Decibel Vol USCG APPROVED
$9.18
Time Remaining: 25d 20h 54m
Buy It Now for only: $9.18

Hand Held Air Horn Pump Super Loud Noise Maker Safety Parties Sports Events Lot
Hand Held Air Horn Pump Super Loud Noise Maker Safety Parties Sports Events Lot
$5.99
Time Remaining: 29d 21h 54m
Buy It Now for only: $5.99

SALE Hand Held Air Horn Pump Loud Noise Maker Safety Parties Sports BirthdaysZ
SALE Hand Held Air Horn Pump Loud Noise Maker Safety Parties Sports BirthdaysZ
$6.99
Time Remaining: 3d 15h 31m
Buy It Now for only: $6.99

Manual Pump Air Horn Hand Held Loud Noise Maker Party Sports Safety Halloween
Manual Pump Air Horn Hand Held Loud Noise Maker Party Sports Safety Halloween
$5.49
Time Remaining: 14h 40m
Buy It Now for only: $5.49

Exfresh portable hand held personal security safety air horn Sports LOUD BLAST
Exfresh portable hand held personal security safety air horn Sports LOUD BLAST
$6.84
Time Remaining: 5d 19h 32m
Buy It Now for only: $6.84

Of course you could always build your own Air Horn...

You will need:

1 - 35 mm film canister

a plastic grocery bag, scissors

5/8" drill bit

3/8" drill bit

3/4" drill bit

a drill

Take the empty plastic 35 mm film canister and cut a 5/8 inch hole in the bottom of the canister and a 3/8 inch hole in the side of the can near the bottom.

Cut a 3/4 inch hole in the lid of the canister. Cover the mouth of the canister with a thin plastic sheet cut from a plastic grocery bag and pop the lid on over it. The plastic sheet now forms a membrane.

Push a length of 5/8" O.D. PVC pipe into it the hole in the bottom of the canister and slide it in until the end of it rests against the membrane. When you blow through the hole in the side of the canister it will give out a tremendously loud tone.

With a little adjustment of the position of the tube, the pressure of the blown into the hole will lift the plastic membrane off the end of the pipe momentarily allowing the air to escape. The tension of the membrane causes it to flap back and the process repeats rapidly causing the noise.