Revenue By Market (Schedule Of Net Revenue By Market)(Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenue, Major Customer [Line Items]
Total Revenue	$ 25,363	$ 21,215
Products and Services Transferred at Point in Time [Member]
Revenue, Major Customer [Line Items]
Total Revenue	9,430	9,035
Products and Services Transferred over Time [Member]
Revenue, Major Customer [Line Items]
Total Revenue	15,933	12,180
Body Worn Devices Segment [Member]
Revenue, Major Customer [Line Items]
Total Revenue	23,572	19,799
Hearing Health Direct-to-Consumer [Member]
Revenue, Major Customer [Line Items]
Total Revenue	1,791	1,416
Medical [Member] | Body Worn Devices Segment [Member]
Revenue, Major Customer [Line Items]
Total Revenue	15,933	12,180
Medical [Member] | Body Worn Devices Segment [Member] | Products and Services Transferred over Time [Member]
Revenue, Major Customer [Line Items]
Total Revenue	15,933	12,180
Hearing Health Market [Member] | Body Worn Devices Segment [Member]
Revenue, Major Customer [Line Items]
Total Revenue	5,810	6,237
Hearing Health Market [Member] | Body Worn Devices Segment [Member] | Products and Services Transferred at Point in Time [Member]
Revenue, Major Customer [Line Items]
Total Revenue	5,810	6,237
Professional Audio Communications [Member] | Body Worn Devices Segment [Member]
Revenue, Major Customer [Line Items]
Total Revenue	1,829	1,382
Professional Audio Communications [Member] | Body Worn Devices Segment [Member] | Products and Services Transferred at Point in Time [Member]
Revenue, Major Customer [Line Items]
Total Revenue	1,829	1,382
Hearing Health Direct-to-consumer (DTC) Market [Member] | Hearing Health Direct-to-Consumer [Member]
Revenue, Major Customer [Line Items]
Total Revenue	1,791	1,416
Hearing Health Direct-to-consumer (DTC) Market [Member] | Hearing Health Direct-to-Consumer [Member] | Products and Services Transferred at Point in Time [Member]
Revenue, Major Customer [Line Items]
Total Revenue	$ 1,791	$ 1,416