Extech sl130 sound level and noise measuring apparatus extech sl 130 p the extech sl130 sound level monitor with display and alarm is ideal for monitoring of noise levels in buildings offices production plants etc the sl 130 has an adjustable alarm function so it can adhere to the legal level checks and if necessary protective measures can be taken p p the sl 130 is also ideally suited as a control instrument at lectures or performances when sound level of the lecture is optimal t