The PC speaker is normally meant to reproduce a square wave via only 2 levels of output (the speaker is driven by only two voltage levels, typically 0 V and 5 V).
For example, if your payments for March and July 2010 were each one month late, the report may continue to show (for seven years from the date after each payment was due) that you were 30 days late twice in 2010, even though the tradeline for that account also shows your payments for the rest of 2010 were made on time.
How long late payments stay on your credit report. A late payment will stay on your credit report for 7 years. However, it will only negatively impact your credit score for 36 months. The newer the late payment is, the more it impacts your credit score. Typically, you can recover from a single 30-day late pay after 12 months of positive payment history.