Ultrasonic

9°C, has the battery failed in the thermometer? It’s colder than this. 6° probably


That SW wind blows strongly some more.
Mosquito is a siren (in the UK anyway) that is meant to repel teenagers. Shops and cafes use them to repel loiterers and they are becoming quite commonplace. The claim is that they can’t be heard by older people and selectively annoy ‘youth’ who then go away.
Explain why I can hear them then! I am 45 years old (as of yesterday).
The device makes a sound rather like the sonar effect you hear on tacky WWII submarine films, only the pitch is octaves higher, as high as the sound bats make I’d say.
I ponder…
Had no luck yet finding the frequency that these things peak at, but Pipistrelle bats begin at 15 and range up to 45KHz. Not sure of the physics at play here, but wouldn’t there be harmonics at an octave above and and another below?
None in my tutor group have ever heard a bat- they said today. I had to ask.

Shot in south Wales.
Advertisements
This entry was posted in Thinking. Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s