The changes in the carrying amount of intangible assets during the years ended December 31, 2019 and 2018 were as follows:

Balance as of January 1, 2018	$	284,408
Additions during the period		46,907
Amortization		(68,496	)
Balance as of December 31, 2018		262,819
Additions during the period		16,737
Amortization		(48,433	)
Balance as of December 31, 2019	$	231,123

Andrea accounts for its long-lived assets in accordance with ASC 360 “Property, Plant and Equipment” for purposes of determining and measuring impairment of its long-lived assets (primarily intangible assets) other than goodwill. Andrea’s policy is to periodically review the value assigned to its long-lived assets to determine if they have been permanently impaired by adverse conditions which may affect Andrea. If Andrea identifies a permanent impairment such that the carrying amount of Andrea’s long-lived assets are not recoverable using the sum of an undiscounted cash flow projection (gross margin dollars from product revenues), a new cost basis for the impaired asset will be established. If required, an impairment charge is recorded based on an estimate of future discounted cash flows. This new cost basis will be net of any recorded impairment. At December 31, 2019 and 2018, Andrea concluded that there were no long-lived assets that were required to be tested for recoverability.

Amortization expense was $48,433 and $68,496 for the years ended December 31, 2019 and 2018, respectively. Patents and trademarks, once issued are amortized on a straight-line basis over periods ranging from 10 to 20 years. Assuming no changes in the Company's intangible assets, estimated amortization expense for each of the five succeeding fiscal years ending December 31 is expected to be approximately $36,000, $27,000, $26,000, $24,000 and $24,000, respectively.