Altec Lansing is a company that has been manufacturing loudspeakers
for a long time. The company name came about when Lansing Manufacturing Company was purchased by WE / Altec in 1939. The 'Lansing' part of the company name refers to J.B.Lansing, the daddy of the company JBL.
Mr Lansing left Altec in 1946 to form Lansing Sound Inc. He hanged himself in 1949, and his life insurance policy ($10,000) bailed his company out of debt. Golly.
Altec Lansing made their reputation with speakers built for cinema and PA. The most famous product was probably the "Voice of the Theatre" speakers. Their drivers still fetch high prices when sold second-hand, a good pair can go for over $500 USD.
I believe that the standard of their products slowly declined over the years, and their newer PA equipment is less sought after.
The company died in 1997, but has since been revived - they now make ceiling speakers, and various speakers for PC audio.
The best static source of information on the company and their products is the unofficial web page, which is maintained by a rabid enthusiast. The "High Efficiency Speaker Asylum" discussion group is also a good information source - roughly a quater of the discussions involve Altec Lansing Drivers.