Voltcraft sl 451 sound level meter and data logger 31 5hz to 8khz voltcraft sl 451 p the voltcraft sl 451 sound level meter and data logger has an unbeatable set of features in addition to standard features the sl 451 has a data logger and usb port it is protected by a robust housing and moulded protective rubber case making this device is suitable for use in tough conditions p p the device has a measurement range from 30db to 130 db with auto range function the integrated data logg